U.S. patent number 6,844,133 [Application Number 10/230,341] was granted by the patent office on 2005-01-18 for polymer, resist composition and patterning process.
This patent grant is currently assigned to Shin-Etsu Chemical Co., Ltd.. Invention is credited to Koji Hasegawa, Takeshi Kinsho, Tsunehiro Nishi.
United States Patent |
6,844,133 |
Nishi , et al. |
January 18, 2005 |
Polymer, resist composition and patterning process
Abstract
A polymer comprising recurring units of formula (1) wherein
R.sup.1 is H or methyl, R.sup.2 is H or C.sub.1-8 alkyl, R.sup.3 is
CO.sub.2 R.sup.4, and R.sup.4 is C.sub.1-15 alkyl and recurring
units having a carboxylic acid protected with an acid-decomposable
protecting group containing an adamantane structure or
tetracyclo-[4.4.0.1.sup.2,5.1.sup.7,10 ]dodecane structure and
having a Mw of 1,000-500,000 is novel. A resist composition
comprising the polymer as a base resin is sensitive to high-energy
radiation, has excellent sensitivity, resolution and etching
resistance and lends itself to micropatterning with electron beams
or deep-UV ##STR1##
Inventors: |
Nishi; Tsunehiro (Niigata-ken,
JP), Hasegawa; Koji (Niigata-ken, JP),
Kinsho; Takeshi (Niigata-ken, JP) |
Assignee: |
Shin-Etsu Chemical Co., Ltd.
(Tokyo, JP)
|
Family
ID: |
19089670 |
Appl.
No.: |
10/230,341 |
Filed: |
August 29, 2002 |
Foreign Application Priority Data
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Aug 31, 2001 [JP] |
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2001-262833 |
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Current U.S.
Class: |
430/270.1;
430/326; 526/282; 526/270; 430/910 |
Current CPC
Class: |
C08F
220/283 (20200201); C08F 220/1818 (20200201); C08F
220/1812 (20200201); C08F 220/1811 (20200201); G03F
7/0397 (20130101); C08F 220/18 (20130101); C08F
220/28 (20130101); Y10S 430/111 (20130101); G03F
7/0045 (20130101) |
Current International
Class: |
C08F
36/00 (20060101); G03F 7/38 (20060101); G03F
7/00 (20060101); G03F 7/40 (20060101); G03F
7/004 (20060101); G03F 7/038 (20060101); G03F
007/004 (); C08F 036/00 () |
Field of
Search: |
;430/270.1,326,905,910,325 ;526/281,282,270,266 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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9-73173 |
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Mar 1997 |
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JP |
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9-90637 |
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Apr 1997 |
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JP |
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3042618 |
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Mar 2000 |
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JP |
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2000-159758 |
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Jun 2000 |
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JP |
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2000-336121 |
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Dec 2000 |
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JP |
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2002-169289 |
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Jun 2002 |
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JP |
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Other References
Computer English translation of JP 2002-169289, Jun. 2002.* .
JPO abstract JP 2002-169289, Jun. 2002..
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Primary Examiner: Ashton; Rosemary
Attorney, Agent or Firm: Birch, Stewart, Kolasch &
Birch, LLP
Claims
What is claimed is:
1. A polymer comprising recurring units of the following general
formula (1) and recurring units of the following general formulas
(2) and/or the following general formula (3), the polymer having a
weight average molecular weight of 1000 to 500,000, ##STR42##
wherein R.sup.1 is hydrogen or methyl, R.sup.2 is hydrogen or a
straight, branched, or cyclic alkyl group having 1 to 8 carbon
atoms, R.sup.3 is CO.sub.2 R.sup.4, R.sup.4 is a straight,
branched, or cyclic alkyl group having 1 to 15 carbon atoms in
which at least one oxygen atom may intervene in any
carbon-to-carbon bond, R.sup.5 and R.sup.7 each are hydrogen or
methyl, and R.sup.6, R.sup.8, and R.sup.9 each are a straight,
branched, or cyclic alkyl group having 1 to 15 carbon atoms.
2. The polymer of claim 1, further comprising recurring units of
the following general formula (4): ##STR43##
wherein R.sup.10 is hydrogen or methyl and R.sup.11 is a straight,
branched, or cyclic alkyl group having 1 to 15 carbon atoms.
3. A resist composition comprising the polymer of claim 1 as a base
resin.
4. A process for forming a resist pattern comprising the steps of:
applying the resist composition of claim 3 onto a substrate to form
a coating, heat treating the coating and then exposing it to
high-energy radiation or electron beam through a photo mask, and
optionally heat treating the exposed coating and developing it with
a developer.
5. A resist composition comprising the polymer of claim 2 as a base
resin.
6. A process for forming a resist pattern comprising the steps of:
applying the resist composition of claim 5 onto a substrate to form
a coating, heat treating the coating and then exposing it to
high-energy radiation or electron beam through a photo mask, and
optionally heat treating the exposed coating and developing it with
a developer.
7. A polymer comprising recurring units of the following general
formula (1) and recurring units of the following general formula
(4), the polymer having a weight average molecular weight of 1000
to 500,000, ##STR44##
wherein R.sup.1 is hydrogen or methyl, R.sup.2 is hydrogen, or a
straight, branched, or cyclic alkyl group having 1 to 8 carbon
atoms, R.sup.3 is CO.sub.2 R.sup.4, R.sup.4 is a straight,
branched, or cyclic alkyl group having 1 to 15 carbon atoms in
which at least one oxygen atom may intervene in any
carbon-to-carbon bond, R.sup.10 is hydrogen or methyl, and R.sup.11
is a straight, branched, or cyclic alkyl group having 1 to 15
carbon atoms.
8. A resist composition comprising the polymer of claim 7 as a base
resin.
9. A process for forming a resist pattern comprising the steps of:
applying the resist composition of claim 7 onto a substrate to form
a coating, heat treating the coating and then exposing it to
high-energy radiation or electron beam through a photo mask, and
optionally heat treating the exposed coating and developing it with
a developer.
Description
This invention relates to (i) a polymer comprising specific
recurring units, (ii) a resist composition comprising the polymer
as a base resin, and (iii) a patterning process using the resist
composition.
BACKGROUND OF THE INVENTION
While a number of recent efforts are being made to achieve a finer
pattern rule in the drive for higher integration and operating
speeds in LSI devices, deep-ultraviolet lithography is thought to
hold particular promise as the next generation in microfabrication
technology. In particular, photolithography using a KrF or ArF
excimer laser as the light source is strongly desired to reach the
practical level as the micropatterning technique capable of
achieving a feature size of 0.3 .mu.m or less.
For resist materials for use with KrF excimer lasers,
polyhydroxystyrene having a practical level of transparency and
etching resistance is, in fact, a standard base resin. For resist
materials for use with ArF excimer lasers, polyacrylic or
polymethacrylic acid derivatives containing an adamantane structure
in their side chain are often used as described in JP-A 9-73173 and
JP-A 9-90637. Few of these polymers are regarded as exhibiting
satisfactory performance.
More particularly, resist compositions using derivatives of
polyacrylic or polymethacrylic acid as the base resin exhibit
satisfactory sensitivity and resolution upon pattern formation by
exposure and development, but have extremely low dry etching
resistance. It is possible to improve the dry etching resistance to
some extent by introducing many polycyclic structures as typified
by adamantane structures to increase the carbon density. The
resulting polymers, however, become highly hydrophobic as a whole,
giving rise to undesired phenomena including pattern separation due
to reduced substrate adhesion and development defects due to
developer repellency. Still worse, the polymers substantially lose
solubility in safe solvents such as propylene glycol monomethyl
ether acetate. They are thus practically unacceptable. While a
finer pattern rule is being demanded, there is a need to have a
base resin for resist material which exerts satisfactory
performance with respect to sensitivity and resolution, has
practically acceptable etching resistance, and provides good
adhesion to substrates, affinity to developers and solubility in
solvents.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide (i) a
polymer having a high resolution, practically acceptable etching
resistance, improved substrate adhesion and developer affinity, and
a high solubility in safe solvents such as propylene glycol
monomethyl ether acetate, (ii) a resist composition comprising the
polymer as a base resin, and (iii) a patterning process using the
resist composition.
It has been found that novel polymers comprising recurring units of
the following general formula (1) and recurring units having a
carboxylic acid protected with an acid-decomposable protecting
group containing an adamantane structure or
tetracyclo[4.4.0.1.sup.2,5.1.sup.7,10 ]dodecane structure and
having a weight average molecular weight of 1,000 to 500,000, which
are produced by the method to be described later, have improved
properties as the resist base resin; that a resist composition
comprising the polymer as the base resin has a high resolution,
practically acceptable etching resistance, improved substrate
adhesion, developer affinity, and solvent solubility; and that this
resist composition lends itself to precise micropatterning.
In a first aspect, the invention provides a polymer comprising
recurring units of the following general formula (1) and recurring
units having a carboxylic acid protected with an acid-decomposable
protecting group containing an adamantane structure or
tetracyclo[4.4.0.1.sup.2.5.1.sup.7,10 ]dodecane structure. The
polymer has a weight average molecular weight of 1,000 to 500,000.
##STR2##
Herein R.sup.1 is hydrogen or methyl, R.sup.2 is hydrogen or a
straight, branched or cyclic alkyl group having 1 to 8 carbon
atoms, R.sup.3 is CO.sub.2 R.sup.4, and R.sup.4 is a straight,
branched or cyclic alkyl group having 1 to 15 carbon atoms in which
at least one oxygen atom may intervene in any carbon-to-carbon
bond.
Preferably, the recurring units having a carboxylic acid protected
with an acid-decomposable protecting group containing an adamantane
structure or tetracyclo-[4.4.0.1.sup.2,5.1.sup.7,10 ]dodecane
structure are units of the following general formula (2), (3)
and/or (4). ##STR3##
Herein R.sup.5, R.sup.7 and R.sup.10 each are hydrogen or methyl,
R.sup.6, R.sup.8, R.sup.9 and R.sup.11 each are a straight,
branched or cyclic alkyl group having 1 to 15 carbon atoms.
In a second aspect, the invention provides a resist composition
comprising the inventive polymer as a base resin.
In a third aspect, the invention provides a process for forming a
resist pattern comprising the steps of applying the resist
composition onto a substrate to form a coating; heat treating the
coating and then exposing it to high-energy radiation or electron
beam through a photo mask; and optionally heat treating the exposed
coating and developing it with a developer.
As described in the preamble, polyacrylic acid or polymethacrylic
acid derivatives generally suffer from very low dry etching
resistance. This drawback can be overcome by introducing
substantial amounts of units containing polycyclic structures,
typically adamantane structures. However, the resulting polymers as
a whole become highly hydrophobic, detracting from substrate
adhesion, developer affinity, and solvent solubility. Such
inconvenience is avoidable by incorporating units having a specific
bridged ring lactone structure as proposed in Japanese Patent No.
3,042,618. This proposal succeeded in improving substrate adhesion
and developer affinity to some extent while preventing dry etching
resistance from declining. However, particularly when such units
are incorporated in the form of methacrylate, there is still left a
need to improve solubility in safe solvents such as propylene
glycol monomethyl ether acetate. Notably, it is described in
Japanese Patent No. 3,042,618 that when the units were incorporated
in the form of acrylate, the resulting polymer was dissolvable in
propylene glycol monomethyl ether acetate. On the other hand,
recurring units of formula (1) have a chainlike ester structure as
well as a bridged ring lactone structure and thus have high
affinity to ester solvents such as propylene glycol monomethyl
ether acetate. The bridged ring structure, lactone structure and
chainlike ester structure impart dry etching resistance, substrate
adhesion and solvent solubility, respectively. Therefore, a resist
composition using as a base resin the polymer comprising recurring
units of formula (1) and recurring units having a carboxylic acid
protected with an acid-decomposable protecting group containing an
adamantane structure or tetracyclo[4.4.0.1.sup.2,5.1.sup.7,10
]dodecane structure according to the invention satisfies the
performance factors of sensitivity and resolution, has practically
acceptable dry etching resistance, is improved in substrate
adhesion, developer affinity and solvent solubility, and is thus
very useful in forming micropatterns.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Polymer
Novel polymers or high molecular weight compounds according to the
invention are defined as comprising recurring units of the
following general formula (1) and recurring units having a
carboxylic acid protected with an acid-decomposable protecting
group containing an adamantane structure or
tetracyclo[4.4.0.1.sup.2,5.1.sup.7,10 ]dodecane structure. The
polymers have a weight average molecular weight of 1,000 to
500,000. ##STR4##
Herein R.sup.1 is hydrogen or methyl. R.sup.2 is hydrogen or a
straight, branched or cyclic alkyl group having 1 to 8 carbon
atoms, such as, for example, methyl, ethyl, propyl, isopropyl,
n-butyl, sec-butyl, tert-butyl, tert-amyl, n-pentyl, n-hexyl,
cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl,
cyclohexylmethyl and cyclohexylethyl. R.sup.3 is CO.sub.2 R.sup.4.
R.sup.4 is a straight, branched or cyclic alkyl group having 1 to
15 carbon atoms or a similar alkyl group in which one or more
oxygen atoms intervene in any carbon-to-carbon bond. Suitable alkyl
groups include methyl, ethyl, propyl, isopropyl, n-butyl,
sec-butyl, tert-butyl, tert-amyl, n-pentyl, n-hexyl, cyclopentyl,
cyclohexyl, ethylcyclopentyl, butylcyclopentyl, ethylcyclohexyl,
butylcyclohexyl, adamantyl, ethyladamantyl, and butyladamantyl.
Examples of the alkyl group in which one or more oxygen atoms
intervene in any carbon-to-carbon bond include methoxymethyl,
methoxyethoxymethyl, 1-ethoxyethyl and 2-tetrahydropyranyl.
In the inventive polymers, the recurring units having a carboxylic
acid protected with an acid-decomposable protecting group
containing an adamantane structure or
tetracyclo[4.4.0.1.sup.2,5.1.sup.7,10 ]dodecane structure are
preferably units of at least one of the following general formulae
(2) to (4): ##STR5##
Herein R.sup.5, R.sup.7 and R.sup.10 each are hydrogen or methyl.
R.sup.6 R.sup.8, R.sup.9 and R.sup.11 each are a straight, branched
or cyclic alkyl group having 1 to 15 carbon atoms, examples of
which are as enumerated for R.sup.4.
Illustrative, non-limiting examples of the recurring units of
formula (1) are given below. ##STR6##
Illustrative, non-limiting examples of the recurring units of
formula (2) are given below. ##STR7##
Illustrative, non-limiting examples of the recurring units of
formula (3) are given below. ##STR8##
Illustrative, non-limiting examples of the recurring units of
formula (4) are given below. ##STR9##
If desired, the polymers of the invention may further contain
recurring units of one or more types selected from units of the
following general formulae (M1) to (M9). ##STR10##
Herein, R.sup.001 is hydrogen, methyl or CH.sub.2 CO.sub.2
R.sup.003. R.sup.002 is hydrogen, methyl or CO.sub.2 R.sup.003.
R.sup.003 is a straight, branched or cyclic alkyl group of 1 to 15
carbon atoms. R.sup.004 is hydrogen or a monovalent hydrocarbon
group of 1 to 15 carbon atoms having a carboxyl or hydroxyl group.
At least one of R.sup.005 to R.sup.008 represents a monovalent
hydrocarbon group of 1 to 15 carbon atoms having a carboxyl or
hydroxyl group while the remaining R's independently represent
hydrogen or a straight, branched or cyclic alkyl group of 1 to 15
carbon atoms. Alternatively, R.sup.005 to R.sup.008, taken
together, may form a ring, and in that event, at least one of
R.sup.005 to R.sup.008 is a divalent hydrocarbon group of 1 to 15
carbon atoms having a carboxyl or hydroxyl group, while the
remaining R's are independently single bonds or straight, branched
or cyclic alkylene groups of 1 to 15 carbon atoms. R.sup.009 is a
monovalent hydrocarbon group of 2 to 15 carbon atoms having at
least one partial structure selected from among ether, aldehyde,
ketone, ester, carbonate, acid anhydride, amide and imide. At least
one of R.sup.010 to R.sup.013 is a monovalent hydrocarbon group of
2 to 15 carbon atoms having at least one partial structure selected
from among ether, aldehyde, ketone, ester, carbonate, acid
anhydride, amide and imide, while the remaining R's are
independently hydrogen or straight, branched or cyclic alkyl groups
of 1 to 15 carbon atoms. R.sup.010 to R.sup.013, taken together,
may form a ring, and in that event, at least one of R.sup.010 to
R.sup.013 is a divalent hydrocarbon group of 1 to 15 carbon atoms
having at least one partial structure selected from among ether,
aldehyde, ketone, ester, carbonate, acid anhydride, amide and
imide, while the remaining R's are independently single bonds or
straight, branched or cyclic alkylene groups of 1 to 15 carbon
atoms. R.sup.014 is a polycyclic hydrocarbon group having 7 to 15
carbon atoms or an alkyl group containing a polycyclic hydrocarbon
group. R.sup.015 is an acid labile group. X is CH.sub.2 or an
oxygen atom. Y is --O-- or --(NR.sup.016)-- wherein R.sup.016 is
hydrogen or a straight, branched or cyclic alkyl group of 1 to 15
carbon atoms. Letter k is equal to 0 or 1.
More illustratively, R.sup.001 is hydrogen, methyl or CH.sub.2
CO.sub.2 R.sup.003. R.sup.002 is hydrogen, methyl or CO.sub.2
R.sup.003. R.sup.003 is a straight, branched or cyclic alkyl group
of 1 to 15 carbon atoms, for example, methyl, ethyl, propyl,
isopropyl, n-butyl, sec-butyl, tert-butyl, tert-amyl, n-pentyl,
n-hexyl, cyclopentyl, cyclohexyl, ethylcyclopentyl,
butylcyclopentyl, ethylcyclohexyl, butylcyclohexyl, adamantyl,
ethyladamantyl, and butyladamantyl.
R.sup.004 is hydrogen or a monovalent hydrocarbon group of 1 to 15
carbon atoms having a carboxyl or hydroxyl group, for example,
hydrogen, carboxyethyl, carboxybutyl, carboxycyclopentyl,
carboxycyclohexyl, carboxynorbornyl, carboxyadamantyl,
hydroxyethyl, hydroxybutyl, hydroxycyclopentyl, hydroxycyclohexyl,
hydroxynorbornyl, and hydroxyadamantyl.
At least one of R.sup.005 to R.sup.008 represents a monovalent
hydrocarbon group of 1 to 15 carbon atoms having a carboxyl or
hydroxyl group while the remaining R's independently represent
hydrogen or a straight, branched or cyclic alkyl group of 1 to 15
carbon atoms. Examples of the carboxyl or hydroxyl-bearing
monovalent hydrocarbon group of 1 to 15 carbon atoms include
carboxy, carboxymethyl, carboxyethyl, carboxybutyl, hydroxymethyl,
hydroxyethyl, hydroxybutyl, 2-carboxyethoxycarbonyl,
4-carboxybutoxycarbonyl, 2-hydroxyethoxycarbonyl,
4-hydroxybutoxycarbonyl, carboxycyclopentyloxycarbonyl,
carboxycyclohexyloxycarbonyl, carboxynorbornyloxycarbonyl,
carboxyadamantyloxycarbonyl, hydroxycyclopentyloxycarbonyl,
hydroxycyclohexyloxycarbonyl, hydroxynorbornyloxycarbonyl, and
hydroxyadamantyloxycarbonyl. Examples of the straight, branched or
cyclic alkyl group of 1 to 15 carbon atoms are the same as
exemplified for R.sup.003.
Alternatively, R.sup.005 to R.sup.008, taken together, may form a
ring, and in that event, at least one of R.sup.005 to R.sup.008 is
a divalent hydrocarbon group of 1 to 15 carbon atoms having a
carboxyl or hydroxyl group, while the remaining R's are
independently single bonds or straight, branched or cyclic alkylene
groups of 1 to 15 carbon atoms. Examples of the carboxyl or
hydroxyl-bearing divalent hydrocarbon group of 1 to 15 carbon atoms
include the groups exemplified as the carboxyl or hydroxyl-bearing
monovalent hydrocarbon group, with one hydrogen atom eliminated
therefrom. Examples of the straight, branched or cyclic alkylene
groups of 1 to 15 carbon atoms include the groups exemplified for
R.sup.003, with one hydrogen atom eliminated therefrom.
R.sup.009 is a monovalent hydrocarbon group of 2 to 15 carbon atoms
containing at least one partial structure selected from among
ether, aldehyde, ketone, ester, carbonate, acid anhydride, amide
and imide, for example, methoxymethyl, methoxyethoxymethyl,
2-oxooxolan-3-yl, 2-oxooxolan-4-yl, 4,4-dimethyl-2-oxooxolan-3-yl,
4-methyl-2-oxooxan-4-yl, 2-oxo-1,3-dioxolan-4-ylmethyl, and
5-methyl-2-oxooxolan-5-yl.
At least one of R.sup.010 to R.sup.013 is a monovalent hydrocarbon
group of 2 to 15 carbon atoms containing at least one partial
structure selected from among ether, aldehyde, ketone, ester,
carbonate, acid anhydride, amide and imide, while the remaining R's
are independently hydrogen or straight, branched or cyclic alkyl
groups of 1 to 15 carbon atoms. Examples of the monovalent
hydrocarbon group of 2 to 15 carbon atoms containing at least one
partial structure selected from among ether, aldehyde, ketone,
ester, carbonate, acid anhydride, amide and imide include
methoxymethyl, methoxymethoxymethyl, formyl, methylcarbonyl,
formyloxy, acetoxy, pivaloyloxy, formyloxymethyl, acetoxymethyl,
pivaloyloxymethyl, methoxycarbonyl, 2-oxooxolan-3-yloxycarbonyl,
4,4-dimethyl-2-oxooxolan-3-yloxycarbonyl,
4-methyl-2-oxooxan-4-yloxycarbonyl,
2-oxo-1,3-dioxolan-4-ylmethyloxycarbonyl, and
5-methyl-2-oxooxolan-5-yloxycarbonyl. Examples of the straight,
branched or cyclic alkyl groups of 1 to 15 carbon atoms are the
same as exemplified for R.sup.003.
R.sup.010 to R.sup.013, taken together, may form a ring, and in
that event, at least one of R.sup.010 to R.sup.013 is a divalent
hydrocarbon group of 1 to 15 carbon atoms containing at least one
partial structure selected from among ether, aldehyde, ketone,
ester, carbonate, acid anhydride, amide and imide, while the
remaining R's are independently single bonds or straight, branched
or cyclic alkylene groups of 1 to 15 carbon atoms. Examples of the
divalent hydrocarbon group of 1 to 15 carbon atoms containing at
least one partial structure selected from among ether, aldehyde,
ketone, ester, carbonate, acid anhydride, amide and imide include
2-oxapropane-1,3-diyl, 1,1-dimethyl-2-oxapropane-1,3-diyl,
1-oxo-2-oxapropane-1,3-diyl, 1,3-dioxo-2-oxapropane-1,3-diyl,
1-oxo-2-oxabutane-1,4-diyl, and 1,3-dioxo-2-oxabutane-1,4-diyl, as
well as the groups exemplified as the monovalent hydrocarbon group
of 1 to 15 carbon atoms containing at least one partial structure
selected from among ether, aldehyde, ketone, ester, carbonate, acid
anhydride, amide and imide, with one hydrogen atom eliminated
therefrom. Examples of the straight, branched or cyclic alkylene
groups of 1 to 15 carbon atoms include the groups exemplified for
R.sup.003, with one hydrogen atom eliminated therefrom.
R.sup.014 is a polycyclic hydrocarbon group having 7 to 15 carbon
atoms or an alkyl group containing a polycyclic hydrocarbon group,
for example, norbornyl, bicyclo[3.3.1]nonyl,
tricyclo[5.2.1.0.sup.2,6 ]decyl, adamantyl, ethyladamantyl,
butyladamantyl, norbornylmethyl, and adamantylmethyl.
R.sup.015 is an acid labile group, which will be described later. X
is CH.sub.2 or an oxygen atom. Y is --O-- or --(NR.sup.016)--
wherein R.sup.016 is hydrogen or a straight, branched or cyclic
alkyl group of 1 to 15 carbon atoms, such as, for example, methyl,
ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl,
tert-amyl, n-pentyl, n-hexyl, cyclopentyl, cyclohexyl,
ethylcyclopentyl, butylcyclopentyl, ethylcyclohexyl,
butylcyclohexyl, adamantyl, ethyladamantyl and butyladamantyl.
Letter k is equal to 0 or 1.
The acid labile groups represented by R.sup.015 may be selected
from a variety of such groups. Examples of the acid labile group
are groups of the following general formulae (L1) to (L4), tertiary
alkyl groups of 4 to 20 carbon atoms, preferably 4 to 15 carbon
atoms, trialkylsilyl groups in which each alkyl moiety has 1 to 6
carbon atoms, and oxoalkyl groups of 4 to 20 carbon atoms.
##STR11##
In these formulae and throughout the specification, the broken line
denotes a free valence bond. R.sup.L01 and R.sup.L02 are hydrogen
or straight, branched or cyclic alkyl groups of 1 to 18 carbon
atoms, preferably 1 to 10 carbon atoms. Exemplary alkyl groups
include methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl,
tert-butyl, cyclopentyl, cyclohexyl, 2-ethylhexyl, and n-octyl.
R.sup.L03 is a monovalent hydrocarbon group of 1 to 18 carbon
atoms, preferably 1 to 10 carbon atoms, which may contain a hetero
atom such as oxygen, examples of which include unsubstituted
straight, branched or cyclic alkyl groups and straight, branched or
cyclic alkyl groups in which some hydrogen atoms are replaced by
hydroxyl, alkoxy, oxo, amino, alkylamino or the like. Illustrative
examples are the substituted alkyl groups shown below.
##STR12##
A pair of R.sup.L01 and R.sup.L02, R.sup.L01 and R.sup.L03, or
R.sup.L02 and R.sup.L03 may form a ring. Each of R.sup.L01,
R.sup.L02 and R.sup.L03 is a straight or branched alkylene group of
1 to 18 carbon atoms, preferably 1 to 10 carbon atoms when they
form a ring.
R.sup.L04 is a tertiary alkyl group of 4 to 20 carbon atoms,
preferably 4 to 15 carbon atoms, a trialkylsilyl group in which
each alkyl moiety has 1 to 6 carbon atoms, an oxoalkyl group of 4
to 20 carbon atoms, or a group of formula (L1). Exemplary tertiary
alkyl groups are tert-butyl, tert-amyl, 1,1-diethylpropyl,
2-cyclopentylpropan-2-yl, 2-cyclohexylpropan-2-yl,
2-(bicyclo[2.2.1]heptan-2-yl)propan-2-yl,
2-(adamantan-1-yl)propan-2-yl, 1-ethylcyclopentyl,
1-butylcyclopentyl, 1-ethylcyclohexyl, 1-butylcyclohexyl,
1-ethyl-2-cyclopentenyl, 1-ethyl-2-cyclohexenyl,
2-methyl-2-adamantyl, and 2-ethyl-2-adamantyl. Exemplary
trialkylsilyl groups are trimethylsilyl, triethylsilyl, and
dimethyl-tert-butylsilyl. Exemplary oxoalkyl groups are
3-oxocyclohexyl, 4-methyl-2-oxooxan-4-yl, and
5-methyl-2-oxooxolan-5-yl. Letter y is an integer of 0 to 6.
R.sup.L05 is a monovalent hydrocarbon group of 1 to 8 carbon atoms
which may contain a hetero atom or a substituted or unsubstituted
aryl group of 6 to 20 carbon atoms. Examples of the monovalent
hydrocarbon group which may contain a hetero atom include straight,
branched or cyclic alkyl groups such as methyl, ethyl, propyl,
isopropyl, n-butyl, sec-butyl, tert-butyl, tert-amyl, n-pentyl,
n-hexyl, cyclopentyl, and cyclohexyl, and substituted groups in
which some hydrogen atoms on the foregoing groups are substituted
with hydroxyl, alkoxy, carboxy, alkoxycarbonyl, oxo, amino,
alkylamino, cyano, mercapto, alkylthio, sulfo or other groups.
Exemplary aryl groups are phenyl, methylphenyl, naphthyl, anthryl,
phenanthryl, and pyrenyl. Letter m is equal to 0 or 1, n is equal
to 0, 1, 2 or 3, and 2m+n is equal to 2 or 3.
R.sup.L06 is a monovalent hydrocarbon group of 1 to 8 carbon atoms
which may contain a hetero atom or a substituted or unsubstituted
aryl group of 6 to 20 carbon atoms. Examples of these groups are
the same as exemplified for R.sup.L05.
R.sup.L07 to R.sup.L16 independently represent hydrogen or
monovalent hydrocarbon groups of 1 to 15 carbon atoms which may
contain a hetero atom. Exemplary hydrocarbon groups are straight,
branched or cyclic alkyl groups such as methyl, ethyl, propyl,
isopropyl, n-butyl, sec-butyl, tert-butyl, tert-amyl, n-pentyl,
n-hexyl, n-octyl, n-nonyl, n-decyl, cyclopentyl, cyclohexyl,
cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl,
cyclohexylmethyl, cyclohexylethyl and cyclohexylbutyl, and
substituted ones of these groups in which some hydrogen atoms are
replaced by hydroxyl, alkoxy, carboxy, alkoxycarbonyl, oxo, amino,
alkylamino, cyano, mercapto, alkylthio, sulfo or other groups.
Alternatively, R.sup.L07 to R.sup.L16, taken together, form a ring
(for example, a pair of R.sup.L07 and R.sup.L08, R.sup.L07 and
R.sup.L09, R.sup.L08 and R.sup.L10, R.sup.L09 and R.sup.L10,
R.sup.L11 and R.sup.L12, R.sup.L13 and R.sup.L14, or a similar pair
form a ring). Each of R.sup.L07 to R.sup.L16 represents a divalent
C.sub.1 -C.sub.15 hydrocarbon group which may contain a hetero
atom, when they form a ring, examples of which are the ones
exemplified above for the monovalent hydrocarbon groups, with one
hydrogen atom being eliminated. Two of R.sup.L07 to R.sup.L16 which
are attached to adjoining carbon atoms (for example, a pair of
R.sup.L07 and R.sup.L09, R.sup.L09 and R.sup.L15, R.sup.L13 and
R.sup.L15, or a similar pair) may bond together directly to form a
double bond.
Of the acid labile groups of formula (L1), the straight and
branched ones are exemplified by the following groups.
##STR13##
Of the acid labile groups of formula (L1), the cyclic ones are, for
example, tetrahydrofuran-2-yl, 2-methyltetrahydrofuran-2-yl,
tetrahydropyran-2-yl, and 2-methyltetrahydropyran-2-yl.
Examples of the acid labile groups of formula (L2) include
tert-butoxycarbonyl, tert-butoxycarbonylmethyl,
tert-amyloxycarbonyl, tert-amyloxycarbonylmethyl,
1,1-diethylpropyloxycarbonyl, 1,1-diethylpropyloxycarbonylmethyl,
1-ethylcyclopentyloxycarbonyl, 1-ethylcyclopentyloxycarbonylmethyl,
1-ethyl-2-cyclopentenyloxycarbonyl,
1-ethyl-2-cyclopentenyloxycarbonylmethyl,
1-ethoxyethoxycarbonylmethyl, 2-tetrahydropyranyloxycarbonylmethyl,
and 2-tetrahydrofuranyloxycarbonylmethyl groups.
Examples of the acid labile groups of formula (L3) include
1-methylcyclopentyl, 1-ethylcyclopentyl, 1-n-propylcyclopentyl,
1-isopropylcyclopentyl, 1-n-butylcyclopentyl,
1-sec-butylcyclopentyl, 1-cyclohexylcyclopentyl,
1-(4-methoxy-n-butyl)cyclopentyl, 1-methylcyclohexyl,
1-ethylcyclohexyl, 3-methyl-1-cyclopenten-3-yl,
3-ethyl-1-cyclopenten-3-yl, 3-methyl-1-cyclohexen-3-yl, and
3-ethyl-1-cyclohexen-3-yl groups.
The acid labile groups of formula (L4) are exemplified by the
following groups. ##STR14##
Examples of the tertiary alkyl groups of 4 to 20 carbon atoms,
trialkylsilyl groups in which each alkyl moiety has 1 to 6 carbon
atoms, and oxoalkyl groups of 4 to 20 carbon atoms are as
exemplified for R.sup.L04.
The recurring units of formulae (M1) to (M9) are effective for
imparting such desired properties as developer affinity, substrate
adhesion and etching resistance to a resist composition based on a
polymer comprising these recurring units. By adjusting the content
of these recurring units, the performance of the resist composition
can be finely adjusted.
The polymers of the invention have a weight average molecular
weight of about 1,000 to 500,000, preferably about 3,000 to
100,000, as measured by gel permeation chromatography (GPC) using a
polystyrene standard. Outside the range, the etching resistance may
become extremely low and the resolution may become low because a
substantial difference in rate of dissolution before and after
exposure is lost.
The polymer of the invention can be prepared through
copolymerization reaction using a compound of the following general
formula (1a) as a first monomer, at least one compound of the
following general formulae (2a), (3a) and (4a) as a second monomer,
and optionally, one or more members selected from compounds of the
following general formulae (M1a) to (M9a) as subsequent monomers.
##STR15##
Herein, R.sup.1 to R.sup.11 are as defined above. ##STR16##
Herein, k, R.sup.001 to R.sup.015, X, and Y are as defined
above.
By properly adjusting the proportion of the respective monomers
used in the copolymerization reaction, the polymer can be tailored
so that it may exert the preferred performance when blended in
resist compositions.
In addition to (i) the monomer of formula (1a), (ii) the monomer or
monomers of formulas (2a) and/or (3a) and/or (4a), and (iii) the
monomer or monomers of formulae (M1a) to (M9a), the polymer of the
invention may have copolymerized therewith (iv) another monomer
having a carbon-to-carbon double bond other than (i) to (iii).
Examples of the additional monomer (iv) include substituted acrylic
acid esters such as methyl methacrylate, methyl crotonate, dimethyl
maleate, and dimethyl itaconate, unsaturated carboxylic acids such
as maleic acid, fumaric acid and itaconic acid, substituted or
unsubstituted norbornenes such as norbornene and methyl
norbornene-5-carboxylate, and unsaturated acid anhydrides such as
itaconic anhydride.
In the polymers of the invention, the preferred proportion of
recurring units based on the respective monomers is, but not
limited to, in the following range:
(i) 1 to 90 mol %, preferably 5 to 80 mol %, and more preferably 10
to 70 mol % of recurring units of formula (1) based on the monomer
of formula (1a),
(ii) 5 to 90 mol %, preferably 10 to 80 mol %, and more preferably
20 to 70 mol % of recurring units of formula (2) and/or (3) and/or
(4) based on the monomer of formula (2a) and/or (3a) and/or
(4a),
(iii) 0 to 60 mol %, preferably 0 to 40 mol %, and more preferably
0 to 30 mol % of recurring units of formulae (M1) to (M9) based on
the monomers of formulae (M1a) to (M9a), and
(iv) 0 to 60 mol %, preferably 0 to 40 mol %, and more preferably 0
to 30 mol % of recurring units based on another monomer.
The monomer of formula (1a) from which the units of formula (1)
included essentially in the inventive polymers originate can be
prepared by the process described in JP-A 2000-159758. The monomers
of formulae (2a) and (3a) from which the units of formulae (2) and
(3) originate are commercially available and can be prepared by
well-known organic chemistry processes using 2-adamantanone and
1-adamantane carboxylate compounds as the starting material. The
monomer of formula (4a) from which the units of formula (4)
originate can be prepared by the process described in JP-A
2000-336121.
A variety of copolymerization reaction methods may be used for the
preparation of the polymer according to the invention. The
preferred polymerization reaction is radical polymerization.
For radical polymerization, preferred reaction conditions include
(a) a solvent selected from among hydrocarbons such as benzene,
ethers such as tetrahydrofuran, alcohols such as ethanol, and
ketones such as methyl isobutyl ketone, (b) a polymerization
initiator selected from azo compounds such as
2,2'-azobisisobutyronitrile and peroxides such as benzoyl peroxide
and lauroyl peroxide, (c) a temperature of about 0.degree. C. to
about 100.degree. C., and (d) a time of about 1/2 hour to about 48
hours. Reaction conditions outside the described range may be
employed if desired.
Resist Composition
Since the polymer of the invention is useful as the base resin of a
resist composition, the other aspect of the invention provides a
resist composition, especially a chemically amplified positive
resist composition, comprising the polymer. Typically, the resist
composition contains the polymer, a photoacid generator, and an
organic solvent, and other optional components.
Photoacid Generator
The photoacid generator is a compound capable of generating an acid
upon exposure to high energy radiation or electron beams and
includes the following: (i) onium salts of the formula (P1a-1),
(P1a-2) or (P1b), (ii) diazomethane derivatives of the formula
(P2), (iii) glyoxime derivatives of the formula (P3), (iv)
bissulfone derivatives of the formula (P4), (v) sulfonic acid
esters of N-hydroxyimide compounds of the formula (P5), (vi)
.beta.-ketosulfonic acid derivatives, (vii) disulfone derivatives,
(viii) nitrobenzylsulfonate derivatives, and (ix) sulfonate
derivatives.
These photoacid generators are described in detail.
(i) Onium Salts of Formula (P1a-1), (P1a-2) or (P1b): ##STR17##
Herein, R.sup.101a, R.sup.101b and R.sup.101c independently
represent straight, branched or cyclic alkyl, alkenyl, oxoalkyl or
oxoalkenyl groups of 1 to 12 carbon atoms, aryl groups of 6 to 20
carbon atoms, or aralkyl or aryloxoalkyl groups of 7 to 12 carbon
atoms, wherein some or all of the hydrogen atoms may be replaced by
alkoxy or other groups. Also, R.sup.101b and R.sup.101c, taken
together, may form a ring. R.sup.101b and R.sup.101c each are
alkylene groups of 1 to 6 carbon atoms when they form a ring.
K.sup.- is a non-nucleophilic counter ion.
R.sup.101a, R.sup.101b, and R.sup.101c may be the same or different
and are illustrated below. Exemplary alkyl groups include methyl,
ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, pentyl,
hexyl, heptyl, octyl, cyclopentyl, cyclohexyl, cycloheptyl,
cyclopropylmethyl, 4-methylcyclohexyl, cyclohexylmethyl, norbornyl,
and adamantyl. Exemplary alkenyl groups include vinyl, allyl,
propenyl, butenyl, hexenyl, and cyclohexenyl. Exemplary oxoalkyl
groups include 2-oxocyclopentyl and 2-oxocyclohexyl as well as
2-oxopropyl, 2-cyclopentyl-2-oxoethyl, 2-cyclohexyl-2-oxoethyl, and
2-(4-methylcyclohexyl)-2-oxoethyl. Exemplary aryl groups include
phenyl and naphthyl; alkoxyphenyl groups such as p-methoxyphenyl,
m-methoxyphenyl, o-methoxyphenyl, ethoxyphenyl,
p-tert-butoxyphenyl, and m-tert-butoxyphenyl; alkylphenyl groups
such as 2-methylphenyl, 3-methylphenyl, 4-methylphenyl,
ethylphenyl, 4-tert-butylphenyl, 4-butylphenyl, and dimethylphenyl;
alkylnaphthyl groups such as methylnaphthyl and ethylnaphthyl;
alkoxynaphthyl groups such as methoxynaphthyl and ethoxynaphthyl;
dialkylnaphthyl groups such as dimethylnaphthyl and
diethylnaphthyl; and dialkoxynaphthyl groups such as
dimethoxynaphthyl and diethoxynaphthyl. Exemplary aralkyl groups
include benzyl, phenylethyl, and phenethyl. Exemplary aryloxoalkyl
groups are 2-aryl-2-oxoethyl groups such as 2-phenyl-2-oxoethyl,
2-(1-naphthyl)-2-oxoethyl, and 2-(2-naphthyl)-2-oxoethyl. Examples
of the non-nucleophilic counter ion represented by K.sup.- include
halide ions such as chloride and bromide ions, fluoroalkylsulfonate
ions such as triflate, 1,1,1-trifluoroethanesulfonate, and
nonafluorobutanesulfonate, arylsulfonate ions such as tosylate,
benzenesulfonate, 4-fluorobenzenesulfonate, and
1,2,3,4,5-pentafluorobenzenesulfonate, and alkylsulfonate ions such
as mesylate and butanesulfonate. ##STR18##
Herein, R.sup.102a and R.sup.102b independently represent straight,
branched or cyclic alkyl groups of 1 to 8 carbon atoms. R.sup.103
represents a straight, branched or cyclic alkylene groups of 1 to
10 carbon atoms. R.sup.104a and R.sup.104b independently represent
2-oxoalkyl groups of 3 to 7 carbon atoms. K.sup.- is a
non-nucleophilic counter ion.
Illustrative of the groups represented by R.sup.102a and R.sup.102b
are methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl,
tert-butyl, pentyl, hexyl, heptyl, octyl, cyclopentyl, cyclohexyl,
cyclopropylmethyl, 4-methylcyclohexyl, and cyclohexylmethyl.
Illustrative of the groups represented by R.sup.103 are methylene,
ethylene, propylene, butylene, pentylene, hexylene, heptylene,
octylene, nonylene, 1,4-cyclohexylene, 1,2-cyclohexylene,
1,3-cyclopentylene, 1,4-cyclooctylene, and
1,4-cyclohexanedimethylene. Illustrative of the groups represented
by R.sup.104a and R.sup.104b are 2-oxopropyl, 2-oxocyclopentyl,
2-oxocyclohexyl, and 2-oxocycloheptyl. Illustrative examples of the
counter ion represented by K.sup.- are the same as exemplified for
formulae (P1a-1) and (P1a-2).
(ii) Diazomethane Derivatives of Formula (P2) ##STR19##
Herein, R.sup.105 and R.sup.106 independently represent straight,
branched or cyclic alkyl or halogenated alkyl groups of 1 to 12
carbon atoms, aryl or halogenated aryl groups of 6 to 20 carbon
atoms, or aralkyl groups of 7 to 12 carbon atoms.
Of the groups represented by R.sup.105 and R.sup.106, exemplary
alkyl groups include methyl, ethyl, propyl, isopropyl, n-butyl,
sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, amyl,
cyclopentyl, cyclohexyl, cycloheptyl, norbornyl, and adamantyl.
Exemplary halogenated alkyl groups include trifluoromethyl,
1,1,1-trifluoroethyl, 1,1,1-trichloroethyl, and nonafluorobutyl.
Exemplary aryl groups include phenyl; alkoxyphenyl groups such as
p-methoxyphenyl, m-methoxyphenyl, o-methoxyphenyl, ethoxyphenyl,
p-tert-butoxyphenyl, and m-tert-butoxyphenyl; and alkylphenyl
groups such as 2-methylphenyl, 3-methylphenyl, 4-methylphenyl,
ethylphenyl, 4-tert-butylphenyl, 4-butylphenyl, and dimethylphenyl.
Exemplary halogenated aryl groups include fluorophenyl,
chlorophenyl, and 1,2,3,4,5-pentafluorophenyl. Exemplary aralkyl
groups include benzyl and phenethyl.
(iii) Glyoxime Derivatives of Formula (P3) ##STR20##
Herein, R.sup.107, R.sup.108, and R.sup.109 independently represent
straight, branched or cyclic alkyl or halogenated alkyl groups of 1
to 12 carbon atoms, aryl or halogenated aryl groups of 6 to 20
carbon atoms, or aralkyl groups of 7 to 12 carbon atoms. Also,
R.sup.108 and R.sup.109, taken together, may form a ring. R.sup.108
and R.sup.109 each are straight or branched alkylene groups of 1 to
6 carbon atoms when they form a ring.
Illustrative examples of the alkyl, halogenated alkyl, aryl,
halogenated aryl, and aralkyl groups represented by R.sup.107,
R.sup.108, and R.sup.109 are the same as exemplified for R.sup.105
and R.sup.106. Examples of the alkylene groups represented by
R.sup.108 and R.sup.109 include methylene, ethylene, propylene,
butylene, and hexylene.
(iv) Bissulfone Derivatives of Formula (P4) ##STR21##
Herein, R.sup.101a and R.sup.101b are as defined above.
(v) Sulfonic Acid Esters of N-hydroxyimide Compounds of Formula
(P5) ##STR22##
Herein, R.sup.110 is an arylene group of 6 to 10 carbon atoms,
alkylene group of 1 to 6 carbon atoms, or alkenylene group of 2 to
6 carbon atoms wherein some or all of the hydrogen atoms may be
replaced by straight or branched alkyl or alkoxy groups of 1 to 4
carbon atoms, nitro, acetyl, or phenyl groups. R.sup.111 is a
straight, branched or cyclic alkyl group of 1 to 8 carbon atoms,
alkenyl, alkoxyalkyl, phenyl or naphthyl group wherein some or all
of the hydrogen atoms may be replaced by alkyl or alkoxy groups of
1 to 4 carbon atoms, phenyl groups (which may have substituted
thereon an alkyl or alkoxy of 1 to 4 carbon atoms, nitro, or acetyl
group), hetero-aromatic groups of 3 to 5 carbon atoms, or chlorine
or fluorine atoms.
Of the groups represented by R.sup.110, exemplary arylene groups
include 1,2-phenylene and 1,8-naphthylene; exemplary alkylene
groups include methylene, ethylene, trimethylene, tetramethylene,
phenylethylene, and norbornane-2,3-diyl; and exemplary alkenylene
groups include 1,2-vinylene, 1-phenyl-1,2-vinylene, and
5-norbornene-2,3-diyl. Of the groups represented by R.sup.111,
exemplary alkyl groups are as exemplified for R.sup.101a to
R.sup.101c ; exemplary alkenyl groups include vinyl, 1-propenyl,
allyl, 1-butenyl, 3-butenyl, isoprenyl, 1-pentenyl, 3-pentenyl,
4-pentenyl, dimethylallyl, 1-hexenyl, 3-hexenyl, 5-hexenyl,
1-heptenyl, 3-heptenyl, 6-heptenyl, and 7-octenyl; and exemplary
alkoxyalkyl groups include methoxymethyl, ethoxymethyl,
propoxymethyl, butoxymethyl, pentyloxymethyl, hexyloxymethyl,
heptyloxy-methyl, methoxyethyl, ethoxyethyl, propoxyethyl,
butoxyethyl, pentyloxyethyl, hexyloxyethyl, methoxypropyl,
ethoxypropyl, propoxypropyl, butoxypropyl, methoxybutyl,
ethoxybutyl, propoxybutyl, methoxypentyl, ethoxypentyl,
methoxyhexyl, and methoxyheptyl.
Of the substituents on these groups, the alkyl groups of 1 to 4
carbon atoms include methyl, ethyl, propyl, isopropyl, n-butyl,
isobutyl and tert-butyl; the alkoxy groups of 1 to 4 carbon atoms
include methoxy, ethoxy, propoxy, isopropoxy, n-butoxy, isobutoxy,
and tert-butoxy; the phenyl groups which may have substituted
thereon an alkyl or alkoxy of 1 to 4 carbon atoms, nitro, or acetyl
group include phenyl, tolyl, p-tert-butoxyphenyl, p-acetylphenyl
and p-nitrophenyl; the hetero-aromatic groups of 3 to 5 carbon
atoms include pyridyl and furyl.
Illustrative examples of the photoacid generator include:
onium salts such as diphenyliodonium trifluoromethanesulfonate,
(p-tert-butoxyphenyl)phenyliodonium trifluoromethanesulfonate,
diphenyliodonium p-toluenesulfonate,
(p-tert-butoxyphenyl)phenyliodonium p-toluenesulfonate,
triphenylsulfonium trifluoromethanesulfonate,
(p-tert-butoxyphenyl)diphenylsulfonium trifluoromethanesulfonate,
bis(p-tert-butoxyphenyl)phenylsulfonium trifluoromethanesulfonate,
tris(p-tert-butoxyphenyl)sulfonium trifluoromethanesulfonate,
triphenylsulfonium p-toluenesulfonate,
(p-tert-butoxyphenyl)diphenylsulfonium p-toluenesulfonate,
bis(p-tert-butoxyphenyl)phenylsulfonium p-toluenesulfonate,
tris(p-tert-butoxyphenyl)sulfonium p-toluenesulfonate,
triphenylsulfonium nonafluorobutanesulfonate, triphenylsulfonium
butanesulfonate, trimethylsulfonium trifluoromethanesulfonate,
trimethylsulfonium p-toluenesulfonate,
cyclohexylmethyl(2-oxocyclohexyl)sulfonium
trifluoromethanesulfonate,
cyclohexylmethyl(2-oxocyclohexyl)sulfonium p-toluenesulfonate,
dimethylphenylsulfonium trifluoromethanesulfonate,
dimethylphenylsulfonium p-toluenesulfonate,
dicyclohexylphenylsulfonium trifluoromethanesulfonate,
dicyclohexylphenylsulfonium p-toluenesulfonate,
trinaphthylsulfonium trifluoromethanesulfonate,
cyclohexylmethyl(2-oxocyclohexyl)sulfonium
trifluoromethanesulfonate,
(2-norbornyl)methyl(2-oxocyclohexyl)sulfonium
trifluoromethanesulfonate,
ethylenebis[methyl(2-oxocyclopentyl)sulfonium
trifluoromethanesulfonate], and
1,2'-naphthylcarbonylmethyltetrahydrothiophenium triflate;
diazomethane derivatives such as bis(benzenesulfonyl)diazomethane,
bis(p-toluenesulfonyl)diazomethane,
bis(xylenesulfonyl)diazomethane,
bis(cyclohexylsulfonyl)diazomethane,
bis(cyclopentylsulfonyl)diazomethane,
bis(n-butylsulfonyl)diazomethane,
bis(isobutylsulfonyl)diazomethane,
bis(sec-butylsulfonyl)diazomethane,
bis(n-propylsulfonyl)diazomethane,
bis(isopropylsulfonyl)diazomethane,
bis(tert-butylsulfonyl)diazomethane,
bis(n-amylsulfonyl)diazomethane, bis(isoamylsulfonyl)diazomethane,
bis(sec-amylsulfonyl)diazomethane,
bis(tert-amylsulfonyl)diazomethane,
1-cyclohexylsulfonyl-1-(tert-butylsulfonyl)diazomethane,
1-cyclohexylsulfonyl-1-(tert-amylsulfonyl)diazomethane, and
1-tert-amylsulfonyl-1-(tert-butylsulfonyl)diazomethane;
glyoxime derivatives such as
bis-O-(p-toluenesulfonyl)-.alpha.-dimethylglyoxime,
bis-O-(p-toluenesulfonyl)-.alpha.-diphenylglyoxime,
bis-O-(p-toluenesulfonyl)-.alpha.-dicyclohexylglyoxime,
bis-O-(p-toluenesulfonyl)-2,3-pentanedioneglyoxime,
bis-O-(p-toluenesulfonyl)-2-methyl-3,4-pentanedioneglyoxime,
bis-O-(n-butanesulfonyl)-.alpha.-dimethylglyoxime,
bis-O-(n-butanesulfonyl)-.alpha.-diphenylglyoxime,
bis-O-(n-butanesulfonyl)-.alpha.-dicyclohexylglyoxime,
bis-O-(n-butanesulfonyl)-2,3-pentanedioneglyoxime,
bis-O-(n-butanesulfonyl)-2-methyl-3,4-pentanedioneglyoxime,
bis-O-(methanesulfonyl)-.alpha.-dimethylglyoxime,
bis-O-(trifluoromethanesulfonyl)-.alpha.-dimethylglyoxime,
bis-O-(1,1,1-trifluoroethanesulfonyl)-.alpha.-dimethylglyoxime,
bis-O-(tert-butanesulfonyl)-.alpha.-dimethylglyoxime,
bis-O-(perfluorooctanesulfonyl)-.alpha.-dimethylglyoxime,
bis-O-(cyclohexanesulfonyl)-.alpha.-dimethylglyoxime,
bis-O-(benzenesulfonyl)-.alpha.-dimethylglyoxime,
bis-O-(p-fluorobenzenesulfonyl)-.alpha.-dimethylglyoxime,
bis-O-(p-tert-butylbenzenesulfonyl)-.alpha.-dimethylglyoxime,
bis-O-(xylenesulfonyl)-.alpha.-dimethylglyoxime, and
bis-O-(camphorsulfonyl)-.alpha.-dimethylglyoxime;
bissulfone derivatives such as bisnaphthylsulfonylmethane,
bistrifluoromethylsulfonylmethane, bismethylsulfonylmethane,
bisethylsulfonylmethane, bispropylsulfonylmethane,
bisisopropylsulfonylmethane, bis-p-toluenesulfonylmethane, and
bisbenzenesulfonylmethane;
.beta.-ketosulfone derivatives such as
2-cyclohexylcarbonyl-2-(p-toluenesulfonyl)propane and
2-isopropylcarbonyl-2-(p-toluenesulfonyl)propane;
disulfone derivatives such as diphenyl disulfone and dicyclohexyl
disulfone;
nitrobenzyl sulfonate derivatives such as 2,6-dinitrobenzyl
p-toluenesulfonate and 2,4-dinitrobenzyl p-toluenesulfonate;
sulfonic acid ester derivatives such as
1,2,3-tris(methanesulfonyloxy)benzene,
1,2,3-tris(trifluoromethanesulfonyloxy)benzene, and
1,2,3-tris(p-toluenesulfonyloxy)benzene; and
sulfonic acid esters of N-hydroxyimides such as
N-hydroxysuccinimide methanesulfonate, N-hydroxysuccinimide
trifluoromethanesulfonate, N-hydroxysuccinimide ethanesulfonate,
N-hydroxysuccinimide 1-propanesulfonate, N-hydroxysuccinimide
2-propanesulfonate, N-hydroxysuccinimide 1-pentanesulfonate,
N-hydroxysuccinimide 1-octanesulfonate, N-hydroxysuccinimide
p-toluenesulfonate, N-hydroxysuccinimide p-methoxybenzenesulfonate,
N-hydroxysuccinimide 2-chloroethanesulfonate, N-hydroxysuccinimide
benzenesulfonate, N-hydroxysuccinimide
2,4,6-trimethylbenzenesulfonate, N-hydroxysuccinimide
1-naphthalenesulfonate, N-hydroxysuccinimide
2-naphthalenesulfonate, N-hydroxy-2-phenylsuccinimide
methanesulfonate, N-hydroxymaleimide methanesulfonate,
N-hydroxymaleimide ethanesulfonate, N-hydroxy-2-phenylmaleimide
methanesulfonate, N-hydroxyglutarimide methanesulfonate,
N-hydroxyglutarimide benzenesulfonate, N-hydroxyphthalimide
methanesulfonate, N-hydroxyphthalimide benzenesulfonate,
N-hydroxyphthalimide trifluoromethanesulfonate,
N-hydroxyphthalimide p-toluenesulfonate, N-hydroxynaphthalimide
methanesulfonate, N-hydroxynaphthalimide benzenesulfonate,
N-hydroxy-5-norbornene-2,3-dicarboxyimide methanesulfonate,
N-hydroxy-5-norbornene-2,3-dicarboxyimide
trifluoromethanesulfonate, and
N-hydroxy-5-norbornene-2,3-dicarboxyimide p-toluenesulfonate.
Preferred among these photoacid generators are onium salts such as
triphenylsulfonium trifluoromethanesulfonate,
(p-tert-butoxyphenyl)diphenylsulfonium trifluoromethanesulfonate,
tris(p-tert-butoxyphenyl)sulfonium trifluoromethanesulfonate,
triphenylsulfonium p-toluenesulfonate,
(p-tert-butoxyphenyl)diphenylsulfonium p-toluenesulfonate,
tris(p-tert-butoxyphenyl)sulfonium p-toluenesulfonate,
trinaphthylsulfonium trifluoromethanesulfonate,
cyclohexylmethyl(2-oxocyclohexyl)sulfonium
trifluoromethanesulfonate,
(2-norbornyl)methyl(2-oxocylohexyl)sulfonium
trifluoromethanesulfonate, and
1,2'-naphthylcarbonylmethyltetrahydrothiophenium triflate;
diazomethane derivatives such as bis(benzenesulfonyl)diazomethane,
bis(p-toluenesulfonyl)diazomethane,
bis(cyclohexylsulfonyl)diazomethane,
bis(n-butylsulfonyl)diazomethane,
bis(isobutylsulfonyl)diazomethane,
bis(sec-butylsulfonyl)diazomethane,
bis(n-propylsulfonyl)diazomethane,
bis(isopropylsulfonyl)diazomethane, and
bis(tert-butylsulfonyl)diazomethane; glyoxime derivatives such as
bis-O-(p-toluenesulfonyl)-.alpha.-dimethylglyoxime and
bis-O-(n-butanesulfonyl)-.alpha.-dimethylglyoxime; bissulfone
derivatives such as bisnaphthylsulfonylmethane; and sulfonic acid
esters of N-hydroxyimide compounds such as N-hydroxysuccinimide
methanesulfonate, N-hydroxysuccinimide trifluoromethanesulfonate,
N-hydroxysuccinimide 1-propanesulfonate, N-hydroxysuccinimide
2-propanesulfonate, N-hydroxysuccinimide 1-pentanesulfonate,
N-hydroxysuccinimide p-toluenesulfonate, N-hydroxynaphthalimide
methanesulfonate, and N-hydroxynaphthalimide benzenesulfonate.
These photoacid generators may be used singly or in combinations of
two or more thereof. Onium salts are effective for improving
rectangularity, while diazomethane derivatives and glyoxime
derivatives are effective for reducing standing waves. The
combination of an onium salt with a diazomethane or a glyoxime
derivative allows for fine adjustment of the profile.
The photoacid generator is preferably added in an amount of 0.1 to
15 parts, and especially 0.5 to 8 parts by weight, per 100 parts by
weight of the base resin (all parts are by weight, hereinafter).
Less than 0.1 part of the photoacid generator would provide a poor
sensitivity whereas more than 15 parts of the photoacid generator
would adversely affect transparency and resolution.
Organic Solvent
The organic solvent used herein may be any organic solvent in which
the base resin, photoacid generator, and other components are
soluble. Illustrative, non-limiting, examples of the organic
solvent include ketones such as cyclohexanone and
methyl-2-n-amylketone; alcohols such as 3-methoxybutanol,
3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, and
1-ethoxy-2-propanol; ethers such as propylene glycol monomethyl
ether, ethylene glycol monomethyl ether, propylene glycol monoethyl
ether, ethylene glycol monoethyl ether, propylene glycol dimethyl
ether, and diethylene glycol dimethyl ether; and esters such as
propylene glycol monomethyl ether acetate, propylene glycol
monoethyl ether acetate, ethyl lactate, ethyl pyruvate, butyl
acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate,
tert-butyl acetate, tert-butyl propionate, and propylene glycol
mono-tert-butyl ether acetate. These solvents may be used alone or
in combinations of two or more thereof. Of the above organic
solvents, it is recommended to use diethylene glycol dimethyl ether
and 1-ethoxy-2-propanol because the photoacid generator is most
soluble therein, propylene glycol monomethyl ether acetate because
it is a safe solvent, or a mixture thereof.
An appropriate amount of the organic solvent used is about 200 to
1,000 parts, especially about 400 to 800 parts by weight per 100
parts by weight of the base resin.
Other Polymer
To the resist composition of the invention, another polymer
different from the inventive polymer may also be added. The other
polymers that can be added to the resist composition are, for
example, those polymers comprising units of the following formula
(R1) and/or (R2) and having a weight average molecular weight of
about 1,000 to about 500,000, especially about 5,000 to about
100,000 although the other polymers are not limited thereto.
##STR23##
Herein, R.sup.001 is hydrogen, methyl or CH.sub.2 CO.sub.2
R.sup.003. R.sup.002 is hydrogen, methyl or CO.sub.2 R.sup.003.
R.sup.003 is a straight, branched or cyclic alkyl group of 1 to 15
carbon atoms. R.sup.004 is hydrogen or a monovalent hydrocarbon
group of 1 to 15 carbon atoms having a carboxyl or hydroxyl group.
At least one of R.sup.005 to R.sup.008 represents a monovalent
hydrocarbon group of 1 to 15 carbon atoms having a carboxyl or
hydroxyl group while the remaining R's independently represent
hydrogen or a straight, branched or cyclic alkyl group of 1 to 15
carbon atoms. Alternatively, R.sup.005 to R.sup.008, taken
together, may form a ring, and in that event, at least one of
R.sup.005 to R.sup.008 is a divalent hydrocarbon group of 1 to 15
carbon atoms having a carboxyl or hydroxyl group, while the
remaining R's are independently single bonds or straight, branched
or cyclic alkylene groups of 1 to 15 carbon atoms. R.sup.009 is a
monovalent hydrocarbon group of 2 to 15 carbon atoms containing at
least one partial structure selected from among ether, aldehyde,
ketone, ester, carbonate, acid anhydride, amide and imide. At least
one of R.sup.010 to R.sup.013 is a monovalent hydrocarbon group of
2 to 15 carbon atoms containing at least one partial structure
selected from among ether, aldehyde, ketone, ester, carbonate, acid
anhydride, amide and imide, while the remaining R's are
independently hydrogen or straight, branched or cyclic alkyl groups
of 1 to 15 carbon atoms. R.sup.010 to R.sup.013, taken together,
may form a ring, and in that event, at least one of R.sup.010 to
R.sup.013 is a divalent hydrocarbon group of 1 to 15 carbon atoms
containing at least one partial structure selected from among
ether, aldehyde, ketone, ester, carbonate, acid anhydride, amide
and imide, while the remaining R's are independently single bonds
or straight, branched or cyclic alkylene groups of 1 to 15 carbon
atoms. R.sup.014 is a polycyclic hydrocarbon group having 7 to 15
carbon atoms or an alkyl group containing a polycyclic hydrocarbon
group. R.sup.015 is an acid labile group. R.sup.016 is hydrogen or
methyl. R.sup.017 is a straight, branched or cyclic alkyl group of
1 to 8 carbon atoms. X is CH.sub.2 or an oxygen atom. Letter k' is
equal to 0 or 1; a1', a2', a3', b1', b2', b3', c1', c2', c3', d1',
d2', d3', and e' are numbers from 0 to less than 1, satisfying
a1'+a2'+a3'+b1'+b2'+b3'+c1'+c2'+c3'+d1'+d2'+d3'+e'=1; f', g', h',
i', and j' are numbers from 0 to less than 1, satisfying
f'+g'+h'+i'+j'=1; x', y' and z' each are an integer of 0 to 3,
satisfying 1.ltoreq.x'+y'+z'.ltoreq.5 and
1.ltoreq.y'+z'.ltoreq.3.
Exemplary groups of these R's are as exemplified above.
The inventive polymer and the other polymer are preferably blended
in a weight ratio from 100:0 to 10:90, more preferably from 100:0
to 20:80. If the blend ratio of the inventive polymer is below this
range, the resist composition would become poor in some of the
desired properties. The properties of the resist composition can be
adjusted by properly changing the blend ratio of the inventive
polymer.
The other polymer is not limited to one type and a mixture of two
or more other polymers may be added. The use of plural polymers
allows for easy adjustment of resist properties.
Dissolution Regulator
To the resist composition, a dissolution regulator may be added.
The dissolution regulator is a compound having on the molecule at
least two phenolic hydroxyl groups, in which an average of from 0
to 100 mol % of all the hydrogen atoms on the phenolic hydroxyl
groups are replaced with acid labile groups or a compound having on
the molecule at least one carboxyl group, in which an average of 50
to 100 mol % of all the hydrogen atoms on the carboxyl groups are
replaced with acid labile groups, both the compounds having an
average molecular weight within a range of 100 to 1,000, and
preferably 150 to 800.
The degree of substitution of the hydrogen atoms on the phenolic
hydroxyl groups with acid labile groups is on average at least 0
mol %, and preferably at least 30 mol %, of all the phenolic
hydroxyl groups. The upper limit is 100 mol %, and preferably 80
mol %. The degree of substitution of the hydrogen atoms on the
carboxyl groups with acid labile groups is on average at least 50
mol %, and preferably at least 70 mol %, of all the carboxyl
groups, with the upper limit being 100 mol %.
Preferable examples of such compounds having two or more phenolic
hydroxyl groups or compounds having at least one carboxyl group
include those of formulas (D1) to (D14) below. ##STR24##
##STR25##
In these formulas, R.sup.201 and R.sup.202 are each hydrogen or a
straight or branched alkyl or alkenyl of 1 to 8 carbon atoms;
R.sup.203 is hydrogen, a straight or branched alkyl or alkenyl of 1
to 8 carbon atoms, or --(R.sup.207).sub.h --COOH; R.sup.204 is
--(CH.sub.2).sub.i -- (where i=2 to 10), an arylene of 6 to 10
carbon atoms, carbonyl, sulfonyl, an oxygen atom, or a sulfur atom;
R.sup.205 is an alkylene of 1 to 10 carbon atoms, an arylene of 6
to 10 carbon atoms, carbonyl, sulfonyl, an oxygen atom, or a sulfur
atom; R.sup.206 is hydrogen, a straight or branched alkyl or
alkenyl of 1 to 8 carbon atoms, or a hydroxyl-substituted phenyl or
naphthyl; R.sup.207 is a straight or branched alkylene of 1 to 10
carbon atoms; R.sup.208 is hydrogen or hydroxyl; the letter j is an
integer from 0 to 5; u and h are each 0 or 1; s, t, s', t', s", and
t" are each numbers which satisfy s+t=8, s'+t'=5, and s"+t"=4, and
are such that each phenyl skeleton has at least one hydroxyl group;
and .alpha. is a number such that the compounds of formula (D8) or
(D9) have a molecular weight of from 100 to 1,000.
In the above formulas, suitable examples of R.sup.201 and R.sup.202
include hydrogen, methyl, ethyl, butyl, propyl, ethynyl, and
cyclohexyl; suitable examples of R.sup.203 include the same groups
as for R.sup.201 and R.sup.202, as well as --COOH and --CH.sub.2
COOH; suitable examples of R.sup.204 include ethylene, phenylene,
carbonyl, sulfonyl, oxygen, and sulfur; suitable examples of
R.sup.205 include methylene as well as the same groups as for
R.sup.204 ; and suitable examples of R.sup.206 include hydrogen,
methyl, ethyl, butyl, propyl, ethynyl, cyclohexyl, and
hydroxyl-substituted phenyl or naphthyl.
Exemplary acid labile groups on the dissolution regulator include
groups of the following general formulae (L1) to (L4), tertiary
alkyl groups of 4 to 20 carbon atoms, trialkylsilyl groups in which
each of the alkyls has 1 to 6 carbon atoms, and oxoalkyl groups of
4 to 20 carbon atoms. ##STR26##
In these formulas, R.sup.L01 and R.sup.L02 are each hydrogen or a
straight, branched or cyclic alkyl having 1 to 18 carbon atoms; and
R.sup.L03 is a monovalent hydrocarbon group of 1 to 18 carbon atoms
which may contain a heteroatom (e.g., oxygen). A pair of R.sup.L01
and R.sup.L02, a pair of R.sup.L01 and R.sup.L03, or a pair of
R.sup.L02 and R.sup.L03 may together form a ring, with the proviso
that R.sup.L01, R.sup.L02, and R.sup.L03 are each a straight or
branched alkylene of 1 to 18 carbon atoms when they form a ring.
R.sup.L04 is a tertiary alkyl group of 4 to 20 carbon atoms, a
trialkysilyl group in which each of the alkyls has 1 to 6 carbon
atoms, an oxoalkyl group of 4 to 20 carbon atoms, or a group of the
formula (L1). R.sup.L05 is a monovalent hydrocarbon groups of 1 to
8 carbon atoms which may contain a hetero atom or a substituted or
unsubstituted aryl group of 6 to 20 carbon atoms. R.sup.L06 is a
monovalent hydrocarbon group of 1 to 8 carbon atoms which may
contain a hetero atom or a substituted or unsubstituted aryl group
of 6 to 20 carbon atoms. R.sup.L07 to R.sup.L16 independently
represent hydrogen or monovalent hydrocarbon groups of 1 to 15
carbon atoms which may contain a hetero atom. Alternatively,
R.sup.L07 to R.sup.L16, taken together, may form a ring. Each of
R.sup.L07 to R.sup.L16 represents a divalent C.sub.1 -C.sub.15
hydrocarbon group which may contain a hetero atom, when they form a
ring. Two of R.sup.L07 to R.sup.L16 which are attached to adjoining
carbon atoms may bond together directly to form a double bond.
Letter y is an integer of 0 to 6. Letter m is equal to 0 or 1, n is
equal to 0, 1, 2 or 3, and 2m+n is equal to 2 or 3. Illustrative
examples of these groups are as previously exemplified.
The dissolution regulator may be formulated in an amount of 0 to 50
parts, preferably 0 to 40 parts, and more preferably 0 to 30 parts,
per 100 parts of the base resin, and may be used singly or as a
mixture of two or more thereof. The use of more than 50 parts would
lead to slimming of the patterned film, and thus a decline in
resolution.
The dissolution regulator can be synthesized by introducing acid
labile groups into a compound having phenolic hydroxyl or carboxyl
groups in accordance with an organic chemical formulation.
Basic Compound
In the resist composition of the invention, a basic compound may be
blended. A suitable basic compound used herein is a compound
capable of suppressing the rate of diffusion when the acid
generated by the photoacid generator diffuses within the resist
film. The inclusion of this type of basic compound holds down the
rate of acid diffusion within the resist film, resulting in better
resolution. In addition, it suppresses changes in sensitivity
following exposure, thus reducing substrate and environment
dependence, as well as improving the exposure latitude and the
pattern profile.
Examples of basic compounds include primary, secondary, and
tertiary aliphatic amines, mixed amines, aromatic amines,
heterocyclic amines, carboxyl group-bearing nitrogenous compounds,
sulfonyl group-bearing nitrogenous compounds, hydroxyl
group-bearing nitrogenous compounds, hydroxyphenyl group-bearing
nitrogenous compounds, alcoholic nitrogenous compounds, amide
derivatives, and imide derivatives.
Examples of suitable primary aliphatic amines include ammonia,
methylamine, ethylamine, n-propylamine, isopropylamine,
n-butylamine, iso-butylamine, sec-butylamine, tert-butylamine,
pentylamine, tert-amylamine, cyclopentylamine, hexylamine,
cyclohexylamine, heptylamine, octylamine, nonylamine, decylamine,
dodecylamine, cetylamine, methylenediamine, ethylenediamine, and
tetraethylenepentamine. Examples of suitable secondary aliphatic
amines include dimethylamine, diethylamine, di-n-propylamine,
di-iso-propylamine, di-n-butylamine, di-iso-butylamine,
di-sec-butylamine, dipentylamine, dicyclopentylamine, dihexylamine,
dicyclohexylamine, diheptylamine, dioctylamine, dinonylamine,
didecylamine, didodecylamine, dicetylamine,
N,N-dimethylmethylenediamine, N,N-dimethylethylenediamine, and
N,N-dimethyltetraethylenepentamine. Examples of suitable tertiary
aliphatic amines include trimethylamine, triethylamine,
tri-n-propylamine, tri-iso-propylamine, tri-n-butylamine,
tri-iso-butylamine, tri-sec-butylamine, tripentylamine,
tricyclopentylamine, trihexylamine, tricyclohexylamine,
triheptylamine, trioctylamine, trinonylamine, tridecylamine,
tridodecylamine, tricetylamine,
N,N,N',N'-tetramethylmethylenediamine,
N,N,N',N'-tetramethylethylenediamine, and
N,N,N',N'-tetramethyltetraethylenepentamine.
Examples of suitable mixed amines include dimethylethylamine,
methylethylpropylamine, benzylamine, phenethylamine, and
benzyldimethylamine. Examples of suitable aromatic and heterocyclic
amines include aniline derivatives (e.g., aniline, N-methylaniline,
N-ethylaniline, N-propylaniline, N,N-dimethylaniline,
2-methylaniline, 3-methylaniline, 4-methylaniline, ethylaniline,
propylaniline, trimethylaniline, 2-nitroaniline, 3-nitroaniline,
4-nitroaniline, 2,4-dinitroaniline, 2,6-dinitroaniline,
3,5-dinitroaniline, and N,N-dimethyltoluidine),
diphenyl(p-tolyl)amine, methyldiphenylamine, triphenylamine,
phenylenediamine, naphthylamine, diaminonaphthalene, pyrrole
derivatives (e.g., pyrrole, 2H-pyrrole, 1-methylpyrrole,
2,4-dimethylpyrrole, 2,5-dimethylpyrrole, and N-methylpyrrole),
oxazole derivatives (e.g., oxazole and isooxazole), thiazole
derivatives (e.g., thiazole and isothiazole), imidazole derivatives
(e.g., imidazole, 4-methylimidazole, and
4-methyl-2-phenylimidazole), pyrazole derivatives, furazan
derivatives, pyrroline derivatives (e.g., pyrroline and
2-methyl-1-pyrroline), pyrrolidine derivatives (e.g., pyrrolidine,
N-methylpyrrolidine, pyrrolidinone, and N-methylpyrrolidone),
imidazoline derivatives, imidazolidine derivatives, pyridine
derivatives (e.g., pyridine, methylpyridine, ethylpyridine,
propylpyridine, butylpyridine, 4-(1-butylpentyl)pyridine,
dimethylpyridine, trimethylpyridine, triethylpyridine,
phenylpyridine, 3-methyl-2-phenylpyridine, 4-tert-butylpyridine,
diphenylpyridine, benzylpyridine, methoxypyridine, butoxypyridine,
dimethoxypyridine, 1-methyl-2-pyridone, 4-pyrrolidinopyridine,
1-methyl-4-phenylpyridine, 2-(1-ethylpropyl)pyridine,
aminopyridine, and dimethylaminopyridine), pyridazine derivatives,
pyrimidine derivatives, pyrazine derivatives, pyrazoline
derivatives, pyrazolidine derivatives, piperidine derivatives,
piperazine derivatives, morpholine derivatives, indole derivatives,
isoindole derivatives, 1H-indazole derivatives, indoline
derivatives, quinoline derivatives (e.g., quinoline and
3-quinolinecarbonitrile), isoquinoline derivatives, cinnoline
derivatives, quinazoline derivatives, quinoxaline derivatives,
phthalazine derivatives, purine derivatives, pteridine derivatives,
carbazole derivatives, phenanthridine derivatives, acridine
derivatives, phenazine derivatives, 1,10-phenanthroline
derivatives, adenine derivatives, adenosine derivatives, guanine
derivatives, guanosine derivatives, uracil derivatives, and uridine
derivatives.
Examples of suitable carboxyl group-bearing nitrogenous compounds
include aminobenzoic acid, indolecarboxylic acid, and amino acid
derivatives (e.g. nicotinic acid, alanine, alginine, aspartic acid,
glutamic acid, glycine, histidine, isoleucine, glycylleucine,
leucine, methionine, phenylalanine, threonine, lysine,
3-aminopyrazine-2-carboxylic acid, and methoxyalanine). Examples of
suitable sulfonyl group-bearing nitrogenous compounds include
3-pyridinesulfonic acid and pyridinium p-toluenesulfonate. Examples
of suitable hydroxyl group-bearing nitrogenous compounds,
hydroxyphenyl group-bearing nitrogenous compounds, and alcoholic
nitrogenous compounds include 2-hydroxypyridine, aminocresol,
2,4-quinolinediol, 3-indolemethanol hydrate, monoethanolamine,
diethanolamine, triethanolamine, N-ethyldiethanolamine,
N,N-diethylethanolamine, triisopropanolamine, 2,2'-iminodiethanol,
2-aminoethanol, 3-amino-1-propanol, 4-amino-1-butanol,
4-(2-hydroxyethyl)morpholine, 2-(2-hydroxyethyl)pyridine,
1-(2-hydroxyethyl)piperazine,
1-[2-(2-hydroxyethoxy)ethyl]piperazine, piperidine ethanol,
1-(2-hydroxyethyl)pyrrolidine, 1-(2-hydroxyethyl)-2-pyrrolidinone,
3-piperidino-1,2-propanediol, 3-pyrrolidino-1,2-propanediol,
8-hydroxyjulolidine, 3-quinuclidinol, 3-tropanol,
1-methyl-2-pyrrolidine ethanol, 1-aziridine ethanol,
N-(2-hydroxyethyl)phthalimide, and
N-(2-hydroxyethyl)isonicotinamide. Examples of suitable amide
derivatives include formamide, N-methylformamide,
N,N-dimethylformamide, acetamide, N-methylacetamide,
N,N-dimethylacetamide, propionamide, and benzamide. Suitable imide
derivatives include phthalimide, succinimide, and maleimide.
In addition, basic compounds of the following general formula (B1)
may also be included alone or in admixture.
In the formula, n is equal to 1, 2 or 3; Y is independently
hydrogen or a straight, branched or cyclic alkyl group of 1 to 20
carbon atoms which may contain a hydroxyl group or ether; and X is
independently selected from groups of the following general
formulas (X1) to (X3), and two or three X's may bond together to
form a ring. ##STR27##
In the formulas, R.sup.300, R.sup.302 and R.sup.305 are
independently straight or branched alkylene groups of 1 to 4 carbon
atoms; R.sup.301, R.sup.304 and R.sup.306 are independently
hydrogen, straight, branched or cyclic alkyl groups of 1 to 20
carbon atoms, which may contain at least one hydroxyl group, ether
structure, ester structure or lactone ring; and R.sup.303 is a
single bond or a straight or branched alkylene group of 1 to 4
carbon atoms.
Illustrative examples of the compounds of formula (B1) include
tris(2-methoxymethoxyethyl)amine,
tris{2-(2-methoxyethoxy)ethyl}amine,
tris{2-(2-methoxyethoxymethoxy)ethyl}amine,
tris{2-(1-methoxyethoxy)ethyl}amine,
tris{2-(1-ethoxyethoxy)ethyl}amine,
tris{2-(1-ethoxypropoxy)ethyl}amine,
tris[2-{2-(2-hydroxyethoxy)ethoxy}ethyl]amine,
4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane,
4,7,13,18-tetraoxa-1,10-diazabicyclo[8.5.5]eicosane,
1,4,10,13-tetraoxa-7,16-diazabicyclooctadecane, 1-aza-12-crown-4,
1-aza-15-crown-5, 1-aza-18-crown-6, tris(2-formyloxyethyl)amine,
tris(2-acetoxyethyl)amine, tris(2-propionyloxyethyl)amine,
tris(2-butyryloxyethyl)amine, tris(2-isobutyryloxyethyl)amine,
tris(2-valeryloxyethyl)amine, tris(2-pivaloyloxyethyl)amine,
N,N-bis(2-acetoxyethyl)-2-(acetoxyacetoxy)ethylamine,
tris(2-methoxycarbonyloxyethyl)amine,
tris(2-tert-butoxycarbonyloxyethyl)amine,
tris[2-(2-oxopropoxy)ethyl]amine,
tris[2-(methoxycarbonylmethyl)oxyethyl]amine,
tris[2-(tert-butoxycarbonylmethyloxy)ethyl]amine,
tris[2-(cyclohexyloxycarbonylmethyloxy)ethyl]amine,
tris(2-methoxycarbonylethyl)amine,
tris(2-ethoxycarbonylethyl)amine,
N,N-bis(2-hydroxyethyl)-2-(methoxycarbonyl)ethylamine,
N,N-bis(2-acetoxyethyl)-2-(methoxycarbonyl)ethylamine,
N,N-bis(2-hydroxyethyl)-2-(ethoxycarbonyl)ethylamine,
N,N-bis(2-acetoxyethyl)-2-(ethoxycarbonyl)ethylamine,
N,N-bis(2-hydroxyethyl)-2-(2-methoxyethoxycarbonyl)ethylamine,
N,N-bis(2-acetoxyethyl)-2-(2-methoxyethoxycarbonyl)ethylamine,
N,N-bis(2-hydroxyethyl)-2-(2-hydroxyethoxycarbonyl)ethylamine,
N,N-bis(2-acetoxyethyl)-2-(2-acetoxyethoxycarbonyl)ethylamine,
N,N-bis(2-hydroxyethyl)-2-[(methoxycarbonyl)methoxycarbonyl]ethylamine,
N,N-bis(2-acetoxyethyl)-2-[(methoxycarbonyl)methoxycarbonyl]ethylamine,
N,N-bis(2-hydroxyethyl)-2-(2-oxopropoxycarbonyl)ethylamine,
N,N-bis(2-acetoxyethyl)-2-(2-oxopropoxycarbonyl)ethylamine,
N,N-bis(2-hydroxyethyl)-2-(tetrahydrofurfuryloxycarbonyl)ethylamine,
N,N-bis(2-acetoxyethyl)-2-(tetrahydrofurfuryloxycarbonyl)ethylamine,
N,N-bis(2-hydroxyethyl)-2-[(2-oxotetrahydrofuran-3-yl)oxycarbonyl]ethylami
ne,
N,N-bis(2-acetoxyethyl)-2-[(2-oxotetrahydrofuran-3-yl)oxycarbonyl]ethylami
ne, N,N-bis(2-hydroxyethyl)-2-(4-hydroxybutoxycarbonyl)ethylamine,
N,N-bis(2-formyloxyethyl)-2-(4-formyloxybutoxycarbonyl)ethylamine,
N,N-bis(2-formyloxyethyl)-2-(2-formyloxyethoxycarbonyl)ethylamine,
N,N-bis(2-methoxyethyl)-2-(methoxycarbonyl)ethylamine,
N-(2-hydroxyethyl)-bis[2-(methoxycarbonyl)ethyl]amine,
N-(2-acetoxyethyl)-bis[2-(methoxycarbonyl)ethyl]amine,
N-(2-hydroxyethyl)-bis[2-(ethoxycarbonyl)ethyl]amine,
N-(2-acetoxyethyl)-bis[2-(ethoxycarbonyl)ethyl]amine,
N-(3-hydroxy-1-propyl)-bis[2-(methoxycarbonyl)ethyl]amine,
N-(3-acetoxy-1-propyl)-bis[2-(methoxycarbonyl)ethyl]amine,
N-(2-methoxyethyl)-bis[2-(methoxycarbonyl)ethyl]amine,
N-butyl-bis[2-(methoxycarbonyl)ethyl]amine,
N-butyl-bis[2-(2-methoxyethoxycarbonyl)ethyl]amine,
N-methyl-bis(2-acetoxyethyl)amine,
N-ethyl-bis(2-acetoxyethyl)amine,
N-methyl-bis(2-pivaloyloxyethyl)amine,
N-ethyl-bis[2-(methoxycarbonyloxy)ethyl]amine,
N-ethyl-bis[2-(tert-butoxycarbonyloxy)ethyl]amine,
tris(methoxycarbonylmethyl)amine, tris(ethoxycarbonylmethyl)amine,
N-butyl-bis(methoxycarbonylmethyl)amine,
N-hexyl-bis(methoxycarbonylmethyl)amine, and
.beta.-(diethylamino)-.delta.-valerolactone.
Also useful are one or more of cyclic structure-bearing basic
compounds having the following general formula (B2). ##STR28##
Herein X is as defined above, and R.sup.307 is a straight or
branched alkylene group of 2 to 20 carbon atoms which may contain
one or more carbonyl groups, ether structures, ester structures or
sulfide structures.
Illustrative examples of the cyclic structure-bearing basic
compounds having formula (B2) include
1-[2-(methoxymethoxy)ethyl]pyrrolidine,
1-[2-(methoxymethoxy)ethyl]piperidine,
4-[2-(methoxymethoxy)ethyl]morpholine,
1-[2-[(2-methoxyethoxy)methoxy]ethyl]pyrrolidine,
1-[2-[(2-methoxyethoxy)methoxy]ethyl]piperidine,
4-[2-[(2-methoxyethoxy)methoxy]ethyl]morpholine,
2-(1-pyrrolidinyl)ethyl acetate, 2-piperidinoethyl acetate,
2-morpholinoethyl acetate, 2-(1-pyrrolidinyl)ethyl formate,
2-piperidinoethyl propionate, 2-morpholinoethyl acetoxyacetate,
2-(1-pyrrolidinyl)ethyl methoxyacetate,
4-[2-(methoxycarbonyloxy)ethyl]morpholine,
1-[2-(t-butoxycarbonyloxy)ethyl]piperidine,
4-[2-(2-methoxyethoxycarbonyloxy)ethyl]morpholine, methyl
3-(1-pyrrolidinyl)propionate, methyl 3-piperidinopropionate, methyl
3-morpholinopropionate, methyl 3-(thiomorpholino)propionate, methyl
2-methyl-3-(1-pyrrolidinyl)propionate, ethyl
3-morpholinopropionate, methoxycarbonylmethyl
3-piperidinopropionate, 2-hydroxyethyl
3-(1-pyrrolidinyl)propionate, 2-acetoxyethyl
3-morpholinopropionate, 2-oxotetrahydrofuran-3-yl
3-(1-pyrrolidinyl)propionate, tetrahydrofurfuryl
3-morpholinopropionate, glycidyl 3-piperidinopropionate,
2-methoxyethyl 3-morpholinopropionate, 2-(2-methoxyethoxy)ethyl
3-(1-pyrrolidinyl)propionate, butyl 3-morpholinopropionate,
cyclohexyl 3-piperidinopropionate,
.alpha.-(1-pyrrolidinyl)methyl-.gamma.-butyrolactone,
.beta.-piperidino-.gamma.-butyrolactone,
.beta.-morpholino-.delta.-valerolactone, methyl
1-pyrrolidinylacetate, methyl piperidinoacetate, methyl
morpholinoacetate, methyl thiomorpholinoacetate, ethyl
1-pyrrolidinylacetate, and 2-methoxyethyl morpholinoacetate.
Also, one or more of cyano-bearing basic compounds having the
following general formulae (B3) to (B6) may be blended.
##STR29##
Herein, X, R.sup.307 and n are as defined above, and R.sup.308 and
R.sup.309 each are independently a straight or branched alkylene
group of 1 to 4 carbon atoms.
Illustrative examples of the cyano-bearing basic compounds having
formulae (B3) to (B6) include 3-(diethylamino)propiononitrile,
N,N-bis(2-hydroxyethyl)-3-aminopropiononitrile,
N,N-bis(2-acetoxyethyl)-3-aminopropiononitrile,
N,N-bis(2-formyloxyethyl)-3-aminopropiononitrile,
N,N-bis(2-methoxyethyl)-3-aminopropiononitrile,
N,N-bis[2-(methoxymethoxy)ethyl]-3-aminopropiononitrile, methyl
N-(2-cyanoethyl)-N-(2-methoxyethyl)-3-aminopropionate, methyl
N-(2-cyanoethyl)-N-(2-hydroxyethyl)-3-aminopropionate, methyl
N-(2-acetoxyethyl)-N-(2-cyanoethyl)-3-aminopropionate,
N-(2-cyanoethyl)-N-ethyl-3-aminopropiononitrile,
N-(2-cyanoethyl)-N-(2-hydroxyethyl)-3-aminopropiononitrile,
N-(2-acetoxyethyl)-N-(2-cyanoethyl)-3-aminopropiononitrile,
N-(2-cyanoethyl)-N-(2-formyloxyethyl)-3-aminopropiononitrile,
N-(2-cyanoethyl)-N-(2-methoxyethyl)-3-aminopropiononitrile,
N-(2-cyanoethyl)-N-[2-(methoxymethoxy)ethyl]-3-aminopropiononitrile,
N-(2-cyanoethyl)-N-(3-hydroxy-1-propyl)-3-aminopropiononitrile,
N-(3-acetoxy-1-propyl)-N-(2-cyanoethyl)-3-aminopropiononitrile,
N-(2-cyanoethyl)-N-(3-formyloxy-1-propyl)-3-aminopropiononitrile,
N-(2-cyanoethyl)-N-tetrahydrofurfuryl-3-aminopropiononitrile,
N,N-bis(2-cyanoethyl)-3-aminopropiononitrile,
diethylaminoacetonitrile, N,N-bis(2-hydroxyethyl)aminoacetonitrile,
N,N-bis(2-acetoxyethyl)aminoacetonitrile,
N,N-bis(2-formyloxyethyl)aminoacetonitrile,
N,N-bis(2-methoxyethyl)aminoacetonitrile,
N,N-bis[2-(methoxymethoxy)ethyl]aminoacetonitrile, methyl
N-cyanomethyl-N-(2-methoxyethyl)-3-aminopropionate, methyl
N-cyanomethyl-N-(2-hydroxyethyl)-3-aminopropionate, methyl
N-(2-acetoxyethyl)-N-cyanomethyl-3-aminopropionate,
N-cyanomethyl-N-(2-hydroxyethyl)aminoacetonitrile,
N-(2-acetoxyethyl)-N-(cyanomethyl)aminoacetonitrile,
N-cyanomethyl-N-(2-formyloxyethyl)aminoacetonitrile,
N-cyanomethyl-N-(2-methoxyethyl)aminoacetonitrile,
N-cyanomethyl-N-[2-(methoxymethoxy)ethyl]aminoacetonitrile,
N-cyanomethyl-N-(3-hydroxy-1-propyl)aminoacetonitrile,
N-(3-acetoxy-1-propyl)-N-(cyanomethyl)aminoacetonitrile,
N-cyanomethyl-N-(3-formyloxy-1-propyl)aminoacetonitrile,
N,N-bis(cyanomethyl)aminoacetonitrile,
1-pyrrolidinepropiononitrile, 1-piperidinepropiononitrile,
4-morpholinepropiononitrile, 1-pyrrolidineacetonitrile,
1-piperidineacetonitrile, 4-morpholineacetonitrile, cyanomethyl
3-diethylaminopropionate, cyanomethyl
N,N-bis(2-hydroxyethyl)-3-aminopropionate, cyanomethyl
N,N-bis(2-acetoxyethyl)-3-aminopropionate, cyanomethyl
N,N-bis(2-formyloxyethyl)-3-aminopropionate, cyanomethyl
N,N-bis(2-methoxyethyl)-3-aminopropionate, cyanomethyl
N,N-bis[2-(methoxymethoxy)ethyl]-3-aminopropionate, 2-cyanoethyl
3-diethylaminopropionate, 2-cyanoethyl
N,N-bis(2-hydroxyethyl)-3-aminopropionate, 2-cyanoethyl
N,N-bis(2-acetoxyethyl)-3-aminopropionate, 2-cyanoethyl
N,N-bis(2-formyloxyethyl)-3-aminopropionate, 2-cyanoethyl
N,N-bis(2-methoxyethyl)-3-aminopropionate, 2-cyanoethyl
N,N-bis[2-(methoxymethoxy)ethyl]-3-aminopropionate, cyanomethyl
1-pyrrolidinepropionate, cyanomethyl 1-piperidinepropionate,
cyanomethyl 4-morpholinepropionate, 2-cyanoethyl
1-pyrrolidinepropionate, 2-cyanoethyl 1-piperidinepropionate, and
2-cyanoethyl 4-morpholinepropionate.
The basic compound is preferably formulated in an amount of 0.001
to 10 parts, and especially 0.01 to 1 part, per part of the
photoacid generator. Less than 0.001 part of the basic compound may
fail to achieve the desired effects thereof, while the use of more
than 10 parts would result in too low a sensitivity and
resolution.
Other Components
In the resist composition, a compound bearing a .ident.C--COOH
group in a molecule may be blended. Exemplary, non-limiting
compounds bearing a .ident.C--COOH group include one or more
compounds selected from Groups I and II below. Including this
compound improves the PED stability of the resist and ameliorates
edge roughness on nitride film substrates.
Group I:
Compounds in which some or all of the hydrogen atoms on the
phenolic hydroxyl groups of the compounds of general formulas (A1)
to (A10) below have been replaced with --R.sup.401 --COOH (wherein
R.sup.401 is a straight or branched alkylene of 1 to 10 carbon
atoms), and in which the molar ratio C/(C+D) of phenolic hydroxyl
groups (C) to .ident.C--COOH groups (D) in the molecule is from 0.1
to 1.0. ##STR30## ##STR31##
In these formulas, R.sup.408 is hydrogen or methyl; R.sup.402 and
R.sup.403 are each hydrogen or a straight or branched alkyl or
alkenyl of 1 to 8 carbon atoms; R.sup.404 is hydrogen, a straight
or branched alkyl or alkenyl of 1 to 8 carbon atoms, or a
--(R.sup.409).sub.h --COOR' group (R' being hydrogen or --R.sup.409
--COOH); R.sup.405 is --(CH.sub.2).sub.i -- (wherein i is 2 to 10),
an arylene of 6 to 10 carbon atoms, carbonyl, sulfonyl, an oxygen
atom, or a sulfur atom; R.sup.406 is an alkylene of 1 to 10 carbon
atoms, an arylene of 6 to 10 carbon atoms, carbonyl, sulfonyl, an
oxygen atom, or a sulfur atom; R.sup.407 is hydrogen, a straight or
branched alkyl or alkenyl of 1 to 8 carbon atoms, or a
hydroxyl-substituted phenyl or naphthyl; R.sup.409 is a straight or
branched alkylene of 1 to 10 carbon atoms; R.sup.410 is hydrogen, a
straight or branched alkyl or alkenyl of 1 to 8 carbon atoms, or a
--R.sup.411 --COOH group; R.sup.411 is a straight or branched
alkylene of 1 to 10 carbon atoms; the letter j is an integer from 0
to 5; u and h are each 0 or 1; s1, t1, s2, t2, s3, t3, s4, and t4
are each numbers which satisfy s1+t1=8, s2+t2=5, s3+t3=4, and
s4+t4=6, and are such that each phenyl skeleton has at least one
hydroxyl group; .kappa. is a number such that the compound of
formula (A6) may have a weight average molecular weight of 1,000 to
5,000; and .lambda. is a number such that the compound of formula
(A7) may have a weight average molecular weight of 1,000 to
10,000.
Group II:
Compounds of general formulas (A11) to (A15) below. ##STR32##
In these formulas, R.sup.402, R.sup.403, and R.sup.411 are as
defined above; R.sup.412 is hydrogen or hydroxyl; s5 and t5 are
numbers which satisfy s5.gtoreq.0, t5.gtoreq.0, and s5+t5=5; and h'
is equal to 0 or 1.
Illustrative, non-limiting examples of the compound bearing a
.ident.C--COOH group include compounds of the general formulas AI-1
to AI-14 and AII-1 to AII-10 below. ##STR33## ##STR34##
In the above formulas, R" is hydrogen or a CH.sub.2 COOH group such
that the CH.sub.2 COOH group accounts for 10 to 100 mol % of R" in
each compound, .alpha. and .kappa. are as defined above.
##STR35##
The compound bearing a .ident.C--COOH group within the molecule may
be used singly or as combinations of two or more thereof.
The compound bearing a .ident.C--COOH group within the molecule is
added in an amount ranging from 0 to 5 parts, preferably 0.1 to 5
parts, more preferably 0.1 to 3 parts, further preferably 0.1 to 2
parts, per 100 parts of the base resin. More than 5 parts of the
compound can reduce the resolution of the resist composition.
The resist composition of the invention may additionally include an
acetylene alcohol derivative for the purpose of enhancing the shelf
stability. Preferred acetylene alcohol derivatives are those having
the general formula (S1) or (S2) below. ##STR36##
In the formulas, R.sup.501, R.sup.502, R.sup.503, R.sup.504, and
R.sup.505 are each hydrogen or a straight, branched, or cyclic
alkyl of 1 to 8 carbon atoms; and X and Y are each 0 or a positive
number, satisfying 0.ltoreq.X.ltoreq.30, 0.ltoreq.Y.ltoreq.30, and
0.ltoreq.X+Y.ltoreq.40.
Preferable examples of the acetylene alcohol derivative include
Surfynol 61, Surfynol 82, Surfynol 104, Surfynol 104E, Surfynol
104H, Surfynol 104A, Surfynol TG, Surfynol PC, Surfynol 440,
Surfynol 465, and Surfynol 485 from Air Products and Chemicals
Inc., and Surfynol E1004 from Nisshin Chemical Industry K.K.
The acetylene alcohol derivative is preferably added in an amount
of 0.01 to 2% by weight, and more preferably 0.02 to 1% by weight,
per 100% by weight of the resist composition. Less than 0.01% by
weight would be ineffective for improving coating characteristics
and shelf stability, whereas more than 2% by weight would result in
a resist having a low resolution.
The resist composition of the invention may include optional
ingredients, for example, a surfactant which is commonly used for
improving the coating characteristics. Optional ingredients may be
added in conventional amounts so long as this does not compromise
the objects of the invention.
Nonionic surfactants are preferred, examples of which include
perfluoroalkylpolyoxyethylene ethanols, fluorinated alkyl esters,
perfluoroalkylamine oxides, perfluoroalkyl EO-addition products,
and fluorinated organosiloxane compounds. Useful surfactants are
commercially available under the trade names Florade FC-430 and
FC-431 from Sumitomo 3M, Ltd., Surflon S-141, S-145, KH-10, KH-20,
KH-30 and KH-40 from Asahi Glass Co., Ltd., Unidyne DS-401, DS-403
and DS-451 from Daikin Industry Co., Ltd., Megaface F-8151 from
Dai-Nippon Ink & Chemicals, Inc., and X-70-092 and X-70-093
from Shin-Etsu Chemical Co., Ltd. Preferred surfactants are Florade
FC-430 from Sumitomo 3M, Ltd., KH-20 and KH-30 from Asahi Glass
Co., Ltd., and X-70-093 from Shin-Etsu Chemical Co., Ltd.
Pattern formation using the resist composition of the invention may
be carried out by a known lithographic technique. For example, the
resist composition is applied onto a substrate such as a silicon
wafer by spin coating or the like to form a resist film having a
thickness of 0.2 to 2.0 .mu.m, which is then pre-baked on a hot
plate at 60 to 150.degree. C. for 1 to 10 minutes, and preferably
at 80 to 130.degree. C. for 1 to 5 minutes. A patterning mask
having the desired pattern is then placed over the resist film, and
the film exposed through the mask to an electron beam or to
high-energy radiation such as deep-UV rays, an excimer laser, or
x-rays in a dose of about 1 to 200 mJ/cm.sup.2, and preferably
about 5 to 100 mJ/cm.sup.2, then post-exposure baked (PEB) on a hot
plate at 60 to 150.degree. C. for 1 to 5 minutes, and preferably at
80 to 130.degree. C. for 1 to 3 minutes. Finally, development is
carried out using as the developer an aqueous alkali solution, such
as a 0.1 to 5% (preferably 2 to 3%) aqueous solution of
tetramethylammonium hydroxide (TMAH), this being done by a
conventional method such as dipping, puddling, or spraying for a
period of 0.1 to 3 minutes, and preferably 0.5 to 2 minutes. These
steps result in the formation of the desired pattern on the
substrate. Of the various types of high-energy radiation that may
be used, the resist composition of the invention is best suited to
fine pattern formation with, in particular, deep-UV rays having a
wavelength of 248 to 193 nm, an excimer laser, x-rays, or an
electron beam. The desired pattern may not be obtainable outside
the upper and lower limits of the above range.
The resist composition comprising the inventive polymer as a base
resin lends itself to micropatterning with electron beams or
deep-UV rays since it is sensitive to high-energy radiation and has
excellent sensitivity, resolution, and etching resistance.
Especially because of the minimized absorption at the exposure
wavelength of an ArF or KrF excimer laser, a finely defined pattern
having sidewalls perpendicular to the substrate can easily be
formed.
EXAMPLE
Synthesis Examples and Examples are given below by way of
illustration and not by way of limitation. The abbreviation Mw is a
weight average molecular weight as measured by GPC using a
polystyrene standard, and SEM is scanning electron microscope.
Polymers within the scope of the invention were synthesized by the
following procedure.
Synthesis Example 1
Synthesis of Polymer 1
A mixture of 140.0 g of
5-methoxycarbonyl-3-oxo-2-oxatricyclo[4.2.1.0.sup.4,8 ]nonan-9-yl
methacrylate, 117.0 g of 2-methyl-2-adamantyl methacrylate, 1.40 g
of 2-mercaptoethanol, and 642.5 g of tetrahydrofuran was heated at
60.degree. C. To the solution was added 3.28 g of
2,2'-azobisisobutyronitrile. The solution was stirred for 15 hours
while keeping at 60.degree. C. The reaction solution was cooled to
room temperature and dissolved in 500 ml of acetone, which with
vigorous stirring, was added dropwise to 10 liters of isopropyl
alcohol. The resulting solids were collected by filtration and
dried in vacuum at 40.degree. C. for 15 hours, obtaining a polymer
in white powder solid form. The amount was 218.7 g and the yield
was 85.1%. This is designated Polymer 1.
Synthesis Examples 2-12
Synthesis of Polymers 2-12
Polymers 2 to 12 were synthesized by the same procedure as above or
a well-known procedure. ##STR37## ##STR38## ##STR39## ##STR40##
Resist compositions were formulated using inventive polymers as the
base resin and examined for resolution.
Examples 1-18 & Comparative Examples 1-4
Resist compositions were prepared by using Polymers 1 to 12 or
comparative Polymers 13 to 16, shown below, as the base resin, and
dissolving the polymer, a photoacid generator, and a basic compound
in a solvent in accordance with the formulation shown in Tables 1
and 2. These compositions were each filtered through a Teflon.RTM.
filter (pore diameter 0.2 .mu.m), thereby giving resist solutions.
##STR41##
These resist solutions were spin coated onto silicon wafers having
an antireflection film (ARC25 by Nissan Chemical Co., Ltd., 77 nm
thick) coated thereon, then heat treated at 130.degree. C. for 60
seconds to give resist films having a thickness of 375 nm. The
resist films were exposed using an ArF excimer laser stepper (Nikon
Corporation; NA 0.55), then heat treated at 110.degree. C. or
130.degree. C. for 60 seconds, and puddle developed with a solution
of 2.38% tetramethylammonium hydroxide in water for 60 seconds,
thereby giving 1:1 line-and-space patterns.
The wafers as developed were sectioned and observed under sectional
SEM. The optimal dose (Eop, mJ/cm.sup.2) was defined as the
exposure dose which provided a 1:1 resolution at the top and bottom
of a 0.20 .mu.m line-and-space pattern. The resolution of the
resist under evaluation was defined as the minimum line width
(.mu.m) of the lines and spaces that separated at the optimal dose.
The shape of the resist pattern was examined under a SEM and
classified into rectangular, rounded head, T-top, forward taper or
reverse taper. For the rating of developer affinity, it was
observed whether or not the developer was repelled on the wafer
during the puddle development. The resist film was rated "O" for
developer affinity or "X" for developer repellency.
The composition and test results of the resist materials are shown
in Tables 1 and 2. The photoacid generator, basic compound and
solvents used are as follows. It is noted that the solvents
contained 0.01% by weight of surfactant KH-20 (Asahi Glass Co.,
Ltd.). TPSNf: triphenylsulfonium nonafluorobutanesulfonate TPSTf:
triphenylsulfonium trifluoromethanesulfonate TMMEA:
trismethoxymethoxyethylamine TAEA: trisacetoxyethylamine PGMEA:
propylene glycol methyl ether acetate CyHO: cyclohexanone
TABLE 1 Photoacid Basic PEB Resin generator compound Solvent temp.,
Eop, Resolution, Developer Example (pbw) (pbw) (pbw) (pbw) .degree.
C. mJ/cm.sup.2 .mu.m Shape affinity 1 Polymer 1 TPSNf TMMEA PGMEA
130 30.0 0.15 rectangular .largecircle. (80) (1.090) (0.236) (480)
2 Polymer 2 TPSNf TMMEA PGMEA 130 27.0 0.15 rectangular
.largecircle. (80) (1.090) (0.236) (480) 3 Polymer 3 TPSNf TMMEA
PGMEA 130 28.0 0.15 rectangular .largecircle. (80) (1.090) (0.236)
(480) 4 Polymer 4 TPSNf TMMEA PGMEA 130 25.0 0.16 rectangular
.largecircle. (80) (1.090) (0.236) (480) 5 Polymer 5 TPSNf TMMEA
PGMEA 110 29.0 0.15 rectangular .largecircle. (80) (1.090) (0.236)
(480) 6 Polymer 6 TPSNf TMMEA PGMEA 110 26.0 0.15 rectangular
.largecircle. (80) (1.090) (0.236) (480) 7 Polymer 7 TPSNf TMMEA
PGMEA 100 27.0 0.16 rectangular .largecircle. (80) (1.090) (0.236)
(480) 8 Polymer 8 TPSNf TMMEA PGMEA 110 25.0 0.15 rectangular
.largecircle. (80) (1.090) (0.236) (480) 9 Polymer 9 TPSNf TMMEA
PGMEA 110 26.0 0.15 rectangular .largecircle. (80) (1.090) (0.236)
(480) 10 Polymer 10 TPSNf TMMEA PGMEA 115 25.0 0.15 rectangular
.largecircle. (80) (1.090) (0.236) (480) 11 Polymer 11 TPSNf TMMEA
PGMEA 130 30.0 0.15 rectangular .largecircle. (80) (1.090) (0.236)
(480) 12 Polymer 12 TPSNf TMMEA PGMEA 130 30.0 0.15 rectangular
.largecircle. (80) (1.090) (0.236) (480) 13 Polymer 1 TPSTf TMMEA
PGMEA 130 28.0 0.15 rectangular .largecircle. (80) (0.800) (0.236)
(480) 14 Polymer 7 TPSTf TMMEA PGMEA 130 28.0 0.15 rectangular
.largecircle. (80) (0.800) (0.236) (480) 15 Polymer 1 TPSNf TAEA
PGMEA 130 28.0 0.15 rectangular .largecircle. (80) (2.180) (0.462)
(480) 16 Polymer 9 TPSNf TAEA PGMEA 110 25.0 0.15 rectangular
.largecircle. (80) (2.180) (0.462) (480) 17 Polymer 11 TPSNf TAEA
PGMEA 130 29.0 0.15 rectangular .largecircle. (80) (2.180) (0.462)
(480) 18 Polymer 9 TPSNf TAEA PGMEA 110 25.0 0.15 rectangular
.largecircle. (80) (3.270) (0.708) (480)
TABLE 2 Compara- Photoacid Basic PEB tive Resin generator compound
Solvent temp., Eop, Resolution, Developer Example (pbw) (pbw) (pbw)
(pbw) .degree. C. mJ/cm.sup.2 .mu.m Shape affinity 1 Polymer 9
TPSNf TMMEA CyHO 130 28.0 0.16 rectangular X (80) (1.090) (0.236)
(560) 2 Polymer 10 TPSNf TMMEA CyHO 130 32.0 0.17 T-top X (80)
(1.090) (0.236) (560) 3 Polymer 11 TPSNf TMMEA CyHO 130 34.0 0.17
T-top X (80) (1.090) (0.236) (560) 4 Polymer 12 TPSNf TMMEA CyHO
110 30.0 0.16 rectangular X (80) (1.090) (0.236) (560)
It is seen from Tables 1 and 2 that the resist compositions within
the scope of the invention have a high sensitivity and resolution
upon ArF excimer laser exposure and are improved in solvent
dissolution and developer affinity.
Japanese Patent Application No. 2001-262833 is incorporated herein
by reference.
Although some preferred embodiments have been described, many
modifications and variations may be made thereto in light of the
above teachings. It is therefore to be understood that the
invention may be practiced otherwise than as specifically described
without departing from the scope of the appended claims.
* * * * *